Technical specifications

A.7 Analog signal modules (SMs)

A.7 Analog signal modules (SMs)

A.7.1 SM 1231 analog input module specifications

Table A- 112 General specifications

Model SM 1231 AI 4 x 13 bit SM 1231 AI 8 x 13 bit SM 1231 AI 4 x 16 bit

Order number 6ES7 231-4HD30-0XB0 6ES7 231-4HF30-0XB0 6ES7 231-5ND30-0XB0
Dimensions W x H x D (mm) 45 x 100 x 75 45 x 100 x 75 45 x 100 x 75
Weight 180 grams 180 grams 180 grams
Power dissipation 2.2 W 2.3 W 2.0 W
Current consumption (SM Bus) 80 mA 90 mA 80 mA
Current consumption (24 VDC) 45 mA 45 mA 65 mA

Table A- 113 Analog inputs

Model SM 1231 AI 4 x 13 bit SM 1231 AI 8 x 13 bit SM 1231 AI 4 x 16 bit

Number of inputs 4 8 4
Type Voltage or current (differential): Selectable in groups of Voltage or current
2 (differential)
Range ±10 V, ±5 V, ±2.5 V, or 0 to 20 mA ±10 V, ±5 V, ±2.5 V, ±1.25
V, 0 to 20 mA or 4 mA to
20 mA
Full scale range (data word) -27,648 to 27,648 voltage / 0 to 27,648 current
Overshoot/undershoot range Voltage: 32,511 to 27,649 / -27,649 to -32,512 Voltage:
(data word) Current: 32,511 to 27,649 / 0 to -4864 32,511 to 27649 /
Refer to the section on analog input -27,649 to -32,512
ranges for voltage and current Current:(0-20 mA): to
(Page 770). 32,511 to 27,649 /
0 to -4864; 4-20 mA: 32511
to 27,649 /
-1 to -4,864
Overflow/underflow (data word) Voltage: 32,767 to 32,512 / -32,513 to -32,768 Voltage: 32,767 to 32,512 /
Refer to the section on input Current: 32,767 to 32,512 / -4865 to -32,768 -32,513 to -32,768
ranges for voltage and current Current: 0 to 20 mA 32,767
(Page 770). to 32,512 / -4865 to -
32,768
4-20 mA 32,767 to 32,512/
-4,865 to -32,768
Resolution1 12 bits + sign bit 15 bits + sign bit
Maximum withstand voltage/current ±35 V / ±40 mA
Smoothing None, weak, medium, or strong
Refer to the section on step response times (Page 769).
Noise rejection 400, 60, 50, or 10 Hz
Refer to the section on sample rates (Page 769).

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A.7 Analog signal modules (SMs)

Model SM 1231 AI 4 x 13 bit SM 1231 AI 8 x 13 bit SM 1231 AI 4 x 16 bit

Input impedance ≥ 9 MΩ (voltage) / 280 Ω (current) ≥ 1 MΩ (voltage) /
<315 Ω, >280 Ω (current)
Isolation None
Field side to logic 500 VAC
Logic to 24 VDC 500 VAC
Field side to 24 VDC 500 VAC
Channel to channel None
Accuracy (25°C / -20 to 60°C) ±0.1% / ±0.2% of full scale ±0.1% / ±0.3% of full scale
Measuring principle Actual value conversion
Common mode rejection 40 dB, DC to 60 Hz
Operational signal range1 Signal plus common mode voltage must be less than +12 V and greater than -12 V
Cable length (meters) 100 m, twisted and shielded
1 Voltages outside the operational range applied to one channel may cause interference on other channels.

Table A- 114 Diagnostics

Model SM 1231 AI 4 x 13 bit SM 1231 AI 8 x 13 bit SM 1231 AI 4 x 16 bit

Overflow/underflow Yes 1 Yes Yes
24 VDC low voltage Yes Yes Yes
Open wire -- -- 4 to 20 mA range only (if
input is below -4,164; 1.0
mA)
1 For SM 1231 AI 4 x 13 bit: If a voltage greater than +30 VDC or less than -15 VDC is applied to the input, the resulting
value will be unknown and the corresponding overflow or underflow may not be active.

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A.7 Analog signal modules (SMs)

Table A- 115 Wiring diagrams for the analog input SMs

SM 1231 AI 4 x 13 bit (6ES7 231-4HD30-0XB0) SM 1231 AI 8 x 13 bit (6ES7 231-4HF30-0XB0)

X10

X10

X11

X12

X11

X13

Note: Connectors must be gold. See Appendix C, Spare Parts for order number.

Table A- 116 Connector pin locations for SM 1231 AI 4 x 13 bit (6ES7 231-4HD30-0XB0)

Pin X10 (gold) X11 (gold)

1 L+ / 24VDC No connection
2 M / 24VDC No connection
3 GND No connection
4 AI 0+ AI 2+
5 AI 0- AI 2-
6 AI 1+ AI 3+
7 AI 1- AI 3-

Table A- 117 Connector pin locations for SM 1231 AI 8 x 13 bit (6ES7 231-4HF30-0XB0)

Pin X10 (gold) X11 (gold) X12 (gold) X13 (gold)

1 L+ / 24VDC No connection No connection No connection
2 M / 24VDC No connection No connection No connection
3 GND No connection No connection No connection
4 AI 0+ AI 2+ AI 4+ AI 6+
5 AI 0- AI 2- AI 4- AI 6-

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Pin X10 (gold) X11 (gold) X12 (gold) X13 (gold)

6 AI 1+ AI 3+ AI 5+ AI 7+
7 AI 1- AI 3- AI 5- AI 7-

Table A- 118 Wiring diagram for the analog input SM

SM 1231 AI 4 x 16 bit (6ES7 231-5ND30-0XB0)

X10

X11

Note: Connectors must be gold. See Appendix C, Spare Parts for order number.

Table A- 119 Connector pin locations for SM 1231 AI 4 x 16 bit (6ES7 231-5ND30-0XB0)

Pin X10 (gold) X11 (gold)

1 L+ / 24VDC No connection
2 M / 24VDC No connection
3 GND No connection
4 AI 0+ AI 2+
5 AI 0- AI 2-
6 AI 1+ AI 3+
7 AI 1- AI 3-

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A.7 Analog signal modules (SMs)

Note
Unused analog inputs should be shorted.
When the inputs are configured for "current" mode, no current will flow through the input
unless you supply external power to the module.

A.7.2 SM 1232 analog output module specifications

Table A- 120 General specifications

Technical data SM 1232 AQ 2 x 14 bit SM 1232 AQ 4 x 14 bit

Order number 6ES7 232-4HB30-0XB0 6ES7 232-4HD30-0XB0
Dimensions W x H x D (mm) 45 x 100 x 75 45 x 100 x 75
Weight 180 grams 180 grams
Power dissipation 1.8 W 2.0 W
Current consumption (SM Bus) 80 mA 80 mA
Current consumption (24 VDC) 45 mA (no load) 45 mA (no load)

Table A- 121 Analog outputs

Technical data SM 1232 AQ 2 x 14 bit SM 1232 AQ 4 x 14 bit

Number of outputs 2 4
Type Voltage or current Voltage or current
Range ±10 V or 0 to 20 mA ±10 V or 0 to 20 mA
Resolution Voltage: 14 bits Voltage: 14 bits
Current: 13 bits Current: 13 bits
Full scale range (data word) Voltage: -27,648 to 27,648 ; Current: 0 to 27,648
Refer to the output ranges for voltage and current (Page 771).
Accuracy (25°C / -20 to 60°C) ±0.3% / ±0.6% of full scale
Settling time (95% of new value) Voltage: 300 μS (R), 750 μS (1 uF)
Current: 600 μS (1 mH), 2 ms (10 mH)
Load impedance Voltage: ≥ 1000 Ω
Current: ≤ 600 Ω
Behavior on RUN to STOP Last value or substitute value (default value 0)
Isolation (field side to logic) none
Cable length (meters) 100 m twisted and shielded

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A.7 Analog signal modules (SMs)

Table A- 122 Diagnostics

Technical data SM 1232 AQ 2 x 14 bit SM 1232 AQ 4 x 14 bit

Overflow/underflow Yes Yes
Short to ground (voltage mode only) Yes Yes
Wire break (current mode only) Yes Yes
24 VDC low voltage Yes Yes

Table A- 123 Wiring diagrams for the analog output SMs

SM 1232 AQ 2 x 14 bit (6ES7 232-4HB30-0XB0) SM 1232 AQ 4 x 14 bit (6ES7 232-4HD30-0XB0)

X10

X10

X11

X11 X12

X13

Note: Connectors must be gold. See Appendix C, Spare Parts for order number.

Table A- 124 Connector pin locations for SM 1232 AQ 2 x 14 bit (6ES7 232-4HB30-0XB0)

Pin X10 (gold) X11 (gold)

1 L+ / 24VDC No connection
2 M / 24VDC No connection
3 GND No connection
4 No connection AQ 0M
5 No connection AQ 0
6 No connection AQ 1M
7 No connection AQ 1

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A.7 Analog signal modules (SMs)

Table A- 125 Connector pin locations for SM 1232 AQ 4 x 14 bit (6ES7 232-4HD30-0XB0)

Pin X10 (gold) X11 (gold) X12 (gold) X13 (gold)

1 L+ / 24VDC No connection No connection No connection
2 M / 24VDC No connection No connection No connection
3 GND No connection No connection No connection
4 No connection No connection AQ 0M AQ 2M
5 No connection No connection AQ 0 AQ 2
6 No connection No connection AQ 1M AQ 3M
7 No connection No connection AQ 1 AIQ 3

A.7.3 SM 1234 analog input/output module specifications

Table A- 126 General specifications

Technical data SM 1234 AI 4 x 13 bit / AQ 2 x 14 bit

Order number 6ES7 234-4HE30-0XB0
Dimensions W x H x D (mm) 45 x 100 x 75
Weight 220 grams
Power dissipation 2.4 W
Current consumption (SM Bus) 80 mA
Current consumption (24 VDC) 60 mA (no load)

Table A- 127 Analog inputs

Model SM 1234 AI 4 x 13 bit / AQ 2 x 14 bit

Number of inputs 4
Type Voltage or Current (differential): Selectable in groups of 2
Range ±10 V, ±5 V, ±2.5 V, or 0 to 20 mA
Full scale range (data word) -27,648 to 27,648
Overshoot/undershoot range Voltage: 32,511 to 27,649 / -27,649 to -32,512
(data word) Current: 32,511 to 27,649 / 0 to -4864
Refer to the section on input ranges for voltage and current (Page 770).
Overflow/underflow (data word) Voltage: 32,767 to 32,512 / -32,513 to -32,768
Current: 32,767 to 32,512 / -4865 to -32,768
Refer to the section on input ranges for voltage and current (Page 770).
Resolution 12 bits + sign bit
Maximum withstand voltage/current ±35 V / ±40 mA
Smoothing None, weak, medium, or strong
Refer to the section on step response times (Page 769).
Noise rejection 400, 60, 50, or 10 Hz
Refer to the section on sample rates (Page 769).

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A.7 Analog signal modules (SMs)

Model SM 1234 AI 4 x 13 bit / AQ 2 x 14 bit

Input impedance ≥ 9 MΩ (voltage) / 280 Ω (current)
Isolation (field side to logic) None
Accuracy (25 °C / -20 to 60°C) ±0.1% / ±0.2% of full scale
Analog to digital conversion time 625 μs (400 Hz rejection)
Common mode rejection 40 dB, DC to 60 Hz
Operational signal range1 Signal plus common mode voltage must be less than +12 V and greater
than -12 V
Cable length (meters) 100 m, twisted and shielded
1 Voltages outside the operational range applied to one channel may cause interference on other channels.

Table A- 128 Analog outputs

Technical data SM 1234 AI 4 x 13 bit / AQ 2 x 14 bit

Number of outputs 2
Type Voltage or current
Range ±10 V or 0 to 20 mA
Resolution Voltage: 14 bits ; Current: 13 bits
Full scale range (data word) Voltage: -27,648 to 27,648; Current: 0 to 27,648
Refer to to the section on output ranges for voltage and current
(Page 771).
Accuracy (25°C / -20 to 60°C) ±0.3% / ±0.6% of full scale
Settling time (95% of new value) Voltage: 300 μS (R), 750 μS (1 uF)
Current: 600 μS (1 mH), 2 ms (10 mH)
Load impedance Voltage: ≥ 1000 Ω
Current: ≤ 600 Ω
Behavior on RUN to STOP Last value or substitute value (default value 0)
Isolation (field side to logic) none
Cable length (meters) 100 m twisted and shielded

Table A- 129 Diagnostics

Model SM 1234 AI 4 x 13 bit / AQ 2 x 14 bit

Overflow/underflow Yes 1
Short to ground (voltage mode only) Yes on outputs
Wire break (current mode only) Yes on outputs
24 VDC low voltage Yes
1 If a voltage greater than +30 VDC or less than -15 VDC is applied to the input, the resulting value will be unknown and
the corresponding overflow or underflow may not be active.

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A.7 Analog signal modules (SMs)

Table A- 130 Wiring diagrams for the analog input/output SM

SM 1234 AI 4 x 13 Bit / AQ 2 x 14 bit (6ES7 234-4HE30-0XB0)

X10

X11

X12

X13

Note: Connectors must be gold. See Appendix C, Spare Parts for order number.

Table A- 131 Connector pin locations for SM 1234 AI 4 x 13 Bit / AQ 2 x 14 bit (6ES7 234-4HE30-
0XB0)

Pin X10 (gold) X11 (gold) X12 (gold) X13 (gold)

1 L+ / 24VDC No connection No connection No connection
2 M / 24VDC No connection No connection No connection
3 GND No connection No connection No connection
4 AI 0+ AI 2+ No connection AQ 0M
5 AI 0- AI 2- No connection AQ 0
6 AI 1+ AI 3+ No connection AQ 1M
7 AI 1- AI 3- No connection AIQ 1

Note
Unused analog inputs should be shorted.
When the inputs are configured for "current" mode, no current will flow through the input
unless you supply external power to the module.

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A.7.4 Step response of the analog inputs

Table A- 132 Step response (ms), 0 to full-scale measured at 95%

Smoothing selection (sample averaging) Noise reduction/rejection frequency (Integration time selection)
400 Hz (2.5 ms) 60 Hz (16.6 ms) 50 Hz (20 ms) 10 Hz (100 ms)
None (1 cycle): No averaging 4 ms 18 ms 22 ms 100 ms
Weak (4 cycles): 4 samples 9 ms 52 ms 63 ms 320 ms
Medium (16 cycles): 16 samples 32 ms 203 ms 241 ms 1200 ms
Strong (32 cycles): 32 samples 61 ms 400 ms 483 ms 2410 ms
Sample time
 4 AI x 13 bits  0.625 ms  4.17 ms  5 ms  25 ms
 8 AI x 13 bits  1.25 ms  4.17 ms  5 ms  25 ms
 4 AI4 x 16 bits  0.417 ms  0.397 ms  0.400 ms  0.400 ms

A.7.5 Sample time and update times for the analog inputs

Table A- 133 Sample time and update time

Rejection frequency Sample time Module update time for all channels
(Integration time) 4-channel SM 8-channel SM
400 Hz (2.5 ms)  4-channel SM: 0.625 ms 0.625 ms 1.250 ms
 8-channel SM: 1.250 ms
60 Hz (16.6 ms) 4.170 ms 4.17 ms 4.17 ms
50 Hz (20 ms) 5.000 ms 5 ms 5 ms
10 Hz (100 ms) 25.000 ms 25 ms 25 ms

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A.7 Analog signal modules (SMs)

A.7.6 Measurement ranges of the analog inputs for voltage

Table A- 134 Analog input representation for voltage

System Voltage Measuring Range

Decimal Hexadecimal ±10 V ±5 V ±2.5 V ±1.25V 0 to 10 V
32767 7FFF 11.851 V 5.926 V 2.963 V 1.481 V Overflow 11.851 V Overflow
32512 7F00
32511 7EFF 11.759 V 5.879 V 2.940 V 1.470 V Overshoot 11.759 V Overshoot
27649 6C01 range range
27648 6C00 10 V 5V 2.5 V 1.250 V Rated range 10 V Rated
20736 5100 7.5 V 3.75 V 1.875 V 0.938 V 7.5 V range

1 1 361.7 μV 180.8 μV 90.4 μV 45.2 μV 361.7 μV

0 0 0V 0V 0V 0V 0V
-1 FFFF Negative
-20736 AF00 -7.5 V -3.75 V -1.875 V -0.938 V values are
not
-27648 9400 -10 V -5 V -2.5 V -1.250 V supported
-27649 93FF Undershoot
-32512 8100 -11.759 V -5.879 V -2.940 V -1.470 V range

-32513 80FF Underflow

-32768 8000 -11.851 V -5.926 V -2.963 V -1.481 V

A.7.7 Measurement ranges of the analog inputs for current

Table A- 135 Analog input representation for current

System Current measuring range

Decimal Hexidecimal 0 mA to 20 mA 4 mA to 20 mA
32767 7FFF 23.70 mA 22.96 mA Overflow
32512 7F00
32511 7EFF 23.52 mA 22.81 mA Overshoot range
27649 6C01
27648 6C00 20 mA 20 mA Nominal range
20736 5100 15 mA 16 mA
1 1 723.4 nA 4 mA + 578.7 nA
0 0 0 mA 4 mA
-1 FFFF Undershoot range
-4864 ED00 -3.52 mA 1.185 mA
-4865 ECFF Underflow
-32768 8000

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A.7.8 Output (AQ) measurement ranges for voltage and current (SB and SM)

Table A- 136 Analog output representation for voltage

System Voltage Output Range

Decimal Hexadecimal ± 10 V
32767 7FFF See note 1 Overflow
32512 7F00 See note 1
32511 7EFF 11.76 V Overshoot range
27649 6C01
27648 6C00 10 V Rated range
20736 5100 7.5 V
1 1 361.7 μ V
0 0 0V
-1 FFFF -361.7 μ V
-20736 AF00 -7.5 V
-27648 9400 -10 V
-27649 93FF Undershoot range
-32512 8100 -11.76 V
-32513 80FF See note 1 Underflow
-32768 8000 See note 1
1 In an overflow or underflow condition, analog outputs will behave according to the device configuration properties set for
the analog signal module. In the "Reaction to CPU STOP" parameter, select either: Use substitute value or Keep last
value.

Table A- 137 Analog output representation for current

System Current Output Range

Decimal Hexadecimal 0 mA to 20 mA
32767 7FFF See note 1 Overflow
32512 7F00 See note 1
32511 7EFF 23.52 mA Overshoot range
27649 6C01
27648 6C00 20 mA Rated range
20736 5100 15 mA
1 1 723.4 nA
0 0 0 mA
1 In an overflow or underflow condition, analog outputs will behave according to the device configuration properties set for
the analog signal module. In the "Reaction to CPU STOP" parameter, select either: Use substitute value or Keep last
value.

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A.8 Thermocouple and RTD signal modules (SMs)

A.8 Thermocouple and RTD signal modules (SMs)

A.8.1 SM 1231 Thermocouple

Table A- 138 General specifications

Model SM 1231 AI 4 x 16 bit TC SM 1231 AI 8 x 16 bit TC

Order number 6ES7 231-5QD30-0XB0 6ES7 231-5QF30-0XB0
Dimensions W x H x D (mm) 45 x 100 x 75 45 x 100 x 75
Weight 180 grams 190 grams
Power dissipation 1.5 W 1.5 W
Current consumption (SM Bus) 80 mA 80 mA
Current consumption (24 VDC) 1 40 mA 40 mA
1 20.4 to 28.8 VDC (Class 2, Limited Power, or sensor power from PLC)

Table A- 139 Analog inputs

Model SM 1231 AI 4 x 16 bit TC SM 1231 AI 8 x 16 bit TC

Number of inputs 4 8
Range See Thermocouple selection table See Thermocouple selection table
Nominal range (data word) (Page 776). (Page 776).
Overrange/underrange (data word)
Overflow/underflow (data word)
Resolution Temperature 0.1° C/0.1° F 0.1° C/0.1° F
Voltage 15 bits plus sign 15 bits plus sign
Maximum withstand voltage ± 35 V ± 35 V
Noise rejection 85 dB for selected filter setting 85 dB for selected filter setting
(10 Hz, 50 Hz, 60 Hz or 400 Hz) (10 Hz, 50 Hz, 60 Hz or 400 Hz)
Common mode rejection > 120 dB at 120 VAC > 120 dB at 120 VAC
Impedance ≥ 10 MΩ ≥ 10 MΩ
Isolation Field to logic 500 VAC 500 VAC
Field to 24 VDC 500 VAC 500 VAC
24 VDC to logic 500 VAC 500 VAC
Channel to channel 120 VAC 120 VAC
Accuracy See Thermocouple selection table See Thermocouple selection table
(Page 776). (Page 776).
Repeatability ±0.05% FS ±0.05% FS
Measuring principle Integrating Integrating
Module update time See Noise reduction selection table See Noise reduction selection table
(Page 776). (Page 776).
Cold junction error ±1.5°C ±1.5°C

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A.8 Thermocouple and RTD signal modules (SMs)

Model SM 1231 AI 4 x 16 bit TC SM 1231 AI 8 x 16 bit TC

Cable length (meters) 100 meters to sensor max. 100 meters to sensor max.
Wire resistance 100 Ω max. 100 Ω max.

Table A- 140 Diagnostics

Model SM 1231 AI 4 x 16 bit TC SM 1231 AI 8 x 16 bit TC

Overflow/underflow 1 Yes Yes
Wire break (current mode only) 2 Yes Yes
24 VDC low voltage 1 Yes Yes
1 The overflow, underflow and low voltage diagnostic alarm information will be reported in the analog data values even if
the alarms are disabled in the module configuration.
2 When wire break alarm is disabled and an open wire condition exists in the sensor wiring, the module may report
random values.

The SM 1231 Thermocouple (TC) analog signal module measures the value of voltage
connected to the module inputs. The temperature measurement type can be either
"Thermocouple" or "Voltage".
● "Thermocouple": The value will be reported in degrees multiplied by ten (for example, 25.3
degrees will be reported as decimal 253).
● "Voltage": The nominal range full scale value will be decimal 27648.

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A.8 Thermocouple and RTD signal modules (SMs)

Table A- 141 Wiring diagrams for the thermocouple SMs

SM 1231 AI 4 x TC 16 bit (6ES7 231-5QD30-0XB0) SM 1231 AI 8 x TC bit (6ES7 231-5QF30-0XB0)

X10 X10

X11

X12

X11
X13

Note: Connectors must be gold. See Appendix C, Spare Parts for order number.

① TC 2, 3, 4, and 5 not shown connected for clarity.

Table A- 142 Connector pin locations for SM 1231 AI 4 x TC 16 bit (6ES7 231-5QD30-0XB0)

Pin X10 (gold) X11 (gold)

1 L+ / 24VDC No connection
2 M / 24VDC No connection
3 GND No connection
4 AI 0+ /TC AI 2+ /TC
5 AI 0- /TC AI 2- /TC
6 AI 1+ /TC AI 3+ /TC
7 AI 1- /TC AI 3- /TC

Table A- 143 Connector Pin Locations for SM 1231 AI 8 x TC bit (6ES7 231-5QF30-0XB0)

Pin X10 (gold) X11 (gold) X12 (gold) X13 (gold)

1 L+ / 24VDC No connection No connection No connection
2 M / 24VDC No connection No connection No connection
3 GND No connection No connection No connection
4 AI 0+ /TC AI 2+ /TC AI 4 I- /TC AI 6 I- /TC
5 AI 0- /TC AI 2- /TC AI 4 I+ /TC AI 6 I+ /TC

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A.8 Thermocouple and RTD signal modules (SMs)

Pin X10 (gold) X11 (gold) X12 (gold) X13 (gold)

6 AI 1+ /TC AI 3+ /TC AI 5 M- /TC AI 7 M- /TC
7 AI 1- /TC AI 3- /TC AI 5 M+ /TC AI 7 M+ /TC

Note
Unused analog inputs should be shorted.
The thermocouple unused channels can be deactivated. No error will occur if an unused
channel is deactivated.

A.8.1.1 Basic operation for a thermocouple

Thermocouples are formed whenever two dissimilar metals are electrically bonded to each
other. A voltage is generated that is proportional to the junction temperature. This voltage is
small; one microvolt could represent many degrees. Measuring the voltage from a
thermocouple, compensating for extra junctions, and then linearizing the result forms the
basis of temperature measurement using thermocouples.
When you connect a thermocouple to the SM 1231 Thermocouple module, the two dissimilar
metal wires are attached to the module at the module signal connector. The place where the
two dissimilar wires are attached to each other forms the sensor thermocouple.
Two more thermocouples are formed where the two dissimilar wires are attached to the
signal connector. The connector temperature causes a voltage that adds to the voltage from
the sensor thermocouple. If this voltage is not corrected, then the temperature reported will
deviate from the sensor temperature.
Cold junction compensation is used to compensate for the connector thermocouple.
Thermocouple tables are based on a reference junction temperature, usually zero degrees
Celsius. The cold junction compensation compensates the connector to zero degrees
Celsius. The cold junction compensation restores the voltage added by the connector
thermocouples. The temperature of the module is measured internally, then converted to a
value to be added to the sensor conversion. The corrected sensor conversion is then
linearized using the thermocouple tables.
For optimum operation of the cold junction compensation, the thermocouple module must be
located in a thermally stable environment. Slow variation (less than 0.1° C/minute) in
ambient module temperature is correctly compensated within the module specifications. Air
movement across the module will also cause cold junction compensation errors.
If better cold junction error compensation is needed, an external iso-thermal terminal block
may be used. The thermocouple module provides for use of a 0° C referenced or 50° C
referenced terminal block.

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A.8 Thermocouple and RTD signal modules (SMs)

A.8.1.2 Selection tables for the SM 1231 thermocouple

The ranges and accuracy for the different thermocouple types supported by the SM 1231
Thermocouple signal module are shown in the table below.

Table A- 144 SM 1231 Thermocouple selection table

Type Under-range Nominal range Nominal range Over-range Normal range 3, 4 Normal range 1, 2
minimum1 low limit high limit maximum2 accuracy @ 25°C accuracy -20°C
to 60°C
J -210.0°C -150.0°C 1200.0°C 1450.0°C ±0.3°C ±0.6°C
K -270.0°C -200.0°C 1372.0°C 1622.0°C ±0.4°C ±1.0°C
T -270.0°C -200.0°C 400.0°C 540.0°C ±0.5°C ±1.0°C
E -270.0°C -200.0°C 1000.0°C 1200.0°C ±0.3°C ±0.6°C
R&S -50.0°C 100.0°C 1768.0°C 2019.0°C ±1.0°C ±2.5°C
N -270.0°C -200.0°C 1300.0°C 1550.0°C ±1.0°C ±1.6°C
C 0.0°C 100.0°C 2315.0°C 2500.0°C ±0.7°C ±2.7°C
TXK/XK(L) -200.0°C -150.0°C 800.0°C 1050.0°C ±0.6°C ±1.2°C
Voltage -32512 -27648 27648 32511 ±0.05% ±0.1%
-80mV 80mV
1 Thermocouple values below the under-range minimum value are reported as -32768.
2 Thermocouple values above the over-range minimum value are reported as 32767.
3 Internal cold junction error is ±1.5°C for all ranges. This adds to the error in this table. The module requires at least 30
minutes of warmup time to meet this specification.
4 In the presence of radiated radio frequency of 970 MHz to 990 MHz, the accuracy of the SM 1231 AI 4 x 16 bit TC may
be degraded.

Table A- 145 Noise reduction and update times for the SM 1231 Thermocouple

Rejection frequency selection Integration time 4 Channel module update 8 Channel module update
time (seconds) time (seconds)
400 Hz (2.5 ms) 10 ms 1 0.143 0.285
60 Hz (16.6 ms) 16.67 ms 0.223 0.445
50 Hz (20 ms) 20 ms 0.263 0.525
10 Hz (100 ms) 100 ms 1.225 2.450
1 To maintain module resolution and accuracy when 400 Hz rejection is selected, the integration time is 10 ms. This
selection also rejects 100 Hz and 200 Hz noise.

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It is recommended for measuring thermocouples that a 100 ms integration time be used. The
use of smaller integration times will increase the repeatability error of the temperature
readings.

Note
After power is applied, the module performs internal calibration for the analog-to-digital
converter. During this time the module reports a value of 32767 on each channel until valid
data is available on that channel. Your user program may need to allow for this initialization
time. Because the configuration of the module can vary the length of the initialization time,
you should verify the behavior of the module in your configuration. If required, you can
include logic in your user program to accommodate the initialization time of the module.

Representation of analog values for Thermocouple Type J

A representation of the analog values of thermocouples type J is shown in the table below.

Table A- 146 Representation of analog values of thermocouples type J

Type J in °C Units Type J in °F Units

Decimal Hexadecimal Decimal Hexadecimal Range
> 1450.0 32767 7FFF > 2642.0 32767 7FFF Overflow
1450.0 14500 38A4 2642.0 26420 6734 Overrange
: : : : : :
1200.1 12001 2EE1 2192.2 21922 55A2
1200.0 12000 2EE0 2192.0 21920 55A0 Rated range
: : : : : :
-150.0 -1500 FA24 -238.0 -2380 F6B4
< -150.0 -32768 8000 < -238.0 -32768 8000 Underflow1
1 Faulty wiring (for example, polarity reversal, or open inputs) or sensor error in the negative
range (for example, wrong type of thermocouple) may cause the thermocouple module to
signal underflow.

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A.8 Thermocouple and RTD signal modules (SMs)

A.8.2 SM 1231 RTD

SM 1231 RTD specifications

Table A- 147 General specifications

Technical data SM 1231 AI 4 x RTD x 16 bit SM 1231 AI 8 x RTD x 16 bit

Order number 6ES7 231-5PD30-0XB0 6ES7 231-5PF30-0XB0
Dimensions W x H x D (mm) 45 x 100 x 75 70 x 100 x 75
Weight 220 grams 270 grams
Power dissipation 1.5 W 1.5 W
Current consumption (SM Bus) 80 mA 90 mA
Current consumption (24 VDC) 1 40 mA 40 mA
1 20.4 to 28.8 VDC (Class 2, Limited Power, or sensor power from CPU)

Table A- 148 Analog inputs

Technical data SM 1231 AI 4 x RTD x 16 bit SM 1231 AI 8 x RTD x16 bit

Number of inputs 4 8
Type Module referenced RTD and Ω Module referenced RTD and Ω
Range See RTD Sensor selection table See RTD Sensor selection table
Nominal range (data word) (Page 781). (Page 781).
Overshoot/undershoot range
(data word)
Overflow/underflow (data word)
Resolution Temperature 0.1° C/0.1° F 0.1° C/0.1° F
Resistance 15 bits plus sign 15 bits plus sign
Maximum withstand voltage ± 35 V ± 35 V
Noise rejection 85 dB for the selected noise reduction 85 dB for the selected noise reduction
(10 Hz, 50 Hz, 60 Hz or 400 Hz) (10 Hz, 50 Hz, 60 Hz or 400 Hz)
Common mode rejection > 120dB > 120dB
Impedance ≥ 10 MΩ ≥ 10 MΩ
Isolation Field side to logic 500 VAC 500 VAC
Field to 24 VDC 500 VAC 500 VAC
24 VDC to logic 500 VAC 500 VAC
Channel to channel isolation none none
Accuracy See RTD Sensor selection table See RTD Sensor selection table
(Page 781). (Page 781).
Repeatability ±0.05% FS ±0.05% FS
Maximum sensor dissipation 0.5m W 0.5m W
Measuring principle Integrating Integrating
Module update time See Noise reduction selection table See Noise reduction selection table
(Page 781). (Page 781).

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Technical data SM 1231 AI 4 x RTD x 16 bit SM 1231 AI 8 x RTD x16 bit

Cable length (meters) 100 meters to sensor max. 100 meters to sensor max.
Wire resistance 20 Ω, 2.7 Ω for 10 Ω RTD max. 20 Ω, 2.7 Ω for 10 Ω RTD max.

Table A- 149 Diagnostics

Technical data SM 1231 AI 4 x RTD x 16 bit SM 1231 AI 8 x RTD x16 bit

Overflow/underflow 1,2 Yes Yes
Wire break 3 Yes Yes
24 VDC low voltage 1 Yes Yes
1 The overflow, underflow and low voltage diagnostic alarm information will be reported in the analog data values even if
the alarms are disabled in the module configuration.
2 For resistance ranges underflow detection is never enabled.
3 When wire break alarm is disabled and an open wire condition exists in the sensor wiring, the module may report
random values.

The SM 1231 RTD analog signal module measures the value of resistance connected to the
module inputs. The measurement type can be selected as either "Resistor" or "Thermal
resistor".
● "Resistor": The nominal range full scale value will be decimal 27648.
● "Thermal resistor": The value will be reported in degrees multiplied by ten (for example,
25.3 degrees will be reported as decimal 253).
The SM 1231 RTD module supports measurements with 2-wire, 3-wire and 4-wire
connections to the sensor resistor.

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A.8 Thermocouple and RTD signal modules (SMs)

Table A- 150 Wiring diagrams for the RTD SMs

SM 1231 RTD 4 x 16 bit (6ES7 231-5PD30-0XB0) SM 1231 RTD 8 x 16 bit (6ES7 231-5PF30-0XB0)

X10
X10

X11
X11

X12

X12

X13

X13

① Loop-back unused RTD inputs

② 2-wire RTD ③ 3-wire RTD ④ 4-wire RTD
NOTE: Note: Connectors must be gold. See Appendix C, Spare Parts for order number.

Table A- 151 Connector Pin Locations for SM 1231 RTD 4 x 16 bit (6ES7 231-5PD30-0XB0)

Pin X10 (gold) X11 (gold) X12 (gold) X13 (gold)

1 L+ / 24VDC No connection No connection No connection
2 M / 24VDC No connection No connection No connection
3 GND No connection No connection No connection
4 AI 0 M+ /RTD AI 1 M+ /RTD AI 2 M+ /RTD AI 3 M+ /RTD
5 AI 0 M- /RTD AI 1 M- /RTD AI 2 M- /RTD AI 3 M- /RTD
6 AI 0 I+ /RTD AI 1 I+ /RTD AI 2 I+ /RTD AI 3 I+ /RTD
7 AI 0 I- /RTD AI 1 I- /RTD AI 2 I- /RTD AI 3 I- /RTD

Table A- 152 Connector Pin Locations for SM 1231 RTD 8 x 16 bit (6ES7 231-5PF30-0XB0)

Pin X10 (gold) X11 (gold) X12 (gold) X13 (gold)

1 L+ / 24VDC No connection No connection No connection
2 M / 24VDC No connection No connection No connection
3 GND No connection No connection No connection
4 AI 0 M+ /RTD AI 2 M+ /RTD AI 4 M+ /RTD AI 6 M+ /RTD
5 AI 0 M- /RTD AI 2 M- /RTD AI 4 M- /RTD AI 6 M- /RTD
6 AI 0 I+ /RTD AI 2 I+ /RTD AI 4 I+ /RTD AI 6 I+ /RTD

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Pin X10 (gold) X11 (gold) X12 (gold) X13 (gold)

7 AI 0 I- /RTD AI 2 I- /RTD AI 4 I- /RTD AI 6 I- /RTD
8 AI 1 M+ /RTD AI 3 M+ /RTD AI 5 M+ /RTD A7 M+ /RTD
9 AI 1 M- /RTD AI 3 M- /RTD AI 5 M- /RTD AI 7 M- /RTD
10 AI 1 I+ /RTD AI 3 I+ /RTD AI 5 I+ /RTD AI 7 I+ /RTD
11 AI 1 I- /RTD AI 3 I- /RTD AI 5 I- /RTD AI 7 I- /RTD

Note
The RTD unused channels can be deactivated. No error will occur if an unused channel is
deactivated.
The RTD module needs to have the current loop continuous to eliminate extra stabilization
time which is automatically added to an unused channel that is not deactivated. For
consistency the RTD module should have a resistor connected (like the 2-wire RTD
connection).

A.8.2.1 Selection tables for the SM 1231 RTD

Table A- 153 Ranges and accuracy for the different sensors supported by the RTD modules

Temperature RTD type Under range Nominal Nominal Over range Normal Normal
coefficient minimum1 range low limit range high maximum2 range range
limit accuracy accuracy
@ 25°C -20°C to
60°C
Pt 0.003850 Pt 10 -243.0°C -200.0°C 850.0°C 1000.0°C ±1.0°C ±2.0°C
ITS90 Pt 50 -243.0°C -200.0°C 850.0°C 1000.0°C ±0.5°C ±1.0°C
DIN EN 60751 Pt 100
Pt 200
Pt 500
Pt 1000
Pt 0.003902 Pt 100 -243.0°C -200.0°C 850.0°C 1000.0°C ± 0.5°C ±1.0°C
Pt 0.003916 Pt 200 -243.0°C -200.0°C 850.0°C 1000.0°C ± 0.5°C ±1.0°C
Pt 0.003920
Pt 500
Pt 1000
Pt 0.003910 Pt 10 -273.2°C -240.0°C 1100.0°C 1295°C ±1.0°C ±2.0°C
Pt 50 -273.2°C -240.0°C 1100.0°C 1295°C ±0.8°C ±1.6°C
Pt 100
Pt 500
Ni 0.006720 Ni 100 -105.0°C -60.0°C 250.0°C 295.0°C ±0.5°C ±1.0°C
Ni 0.006180 Ni 120
Ni 200
Ni 500

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A.8 Thermocouple and RTD signal modules (SMs)

Temperature RTD type Under range Nominal Nominal Over range Normal Normal
coefficient minimum1 range low limit range high maximum2 range range
limit accuracy accuracy
@ 25°C -20°C to
60°C
Ni 1000
LG-Ni 0.005000 LG-Ni 1000 -105.0°C -60.0°C 250.0°C 295.0°C ±0.5°C ±1.0°C
Ni 0.006170 Ni 100 -105.0°C -60.0°C 180.0°C 212.4°C ±0.5°C ±1.0°C
Cu 0.004270 Cu 10 -240.0°C -200.0°C 260.0°C 312.0°C ±1.0°C ±2.0°C
Cu 0.004260 Cu 10 -60.0°C -50.0°C 200.0°C 240.0°C ±1.0°C ±2.0°C
Cu 50 -60.0°C -50.0°C 200.0°C 240.0°C ±0.6°C ±1.2°C
Cu 100
Cu 0.004280 Cu 10 -240.0°C -200.0°C 200.0°C 240.0°C ±1.0°C ±2.0°C
Cu 50 -240.0°C -200.0°C 200.0°C 240.0°C ±0.7°C ±1.4°C
Cu 100
1 RTD values below the under-range minimum value report -32768.
2 RTD values above the over-range maximum value report +32767.

Table A- 154 Resistance

Range Under range Nominal range Nominal range Over range Normal range Normal range
minimum low limit high limit maximum1 accuracy accuracy
@ 25°C -20°C to 60°C
150 Ω n/a 0 (0 Ω) 27648 (150 Ω) 176.383 Ω ±0.05% ±0.1%
300 Ω n/a 0 (0 Ω) 27648 (300 Ω) 352.767 Ω ±0.05% ±0.1%
600 Ω n/a 0 (0 Ω) 27648 (600 Ω) 705.534 Ω ±0.05% ±0.1%
1 Resistance values above the over-range minimum value are reported as +32767.

Note
The module reports 32767 on any activated channel with no sensor connected. If open wire
detection is also enabled, the module flashes the appropriate red LEDs.
When 500 Ω and 1000 Ω RTD ranges are used with other lower value resistors, the error
may increase to two times the specified error.
Best accuracy will be achieved for the 10 Ω RTD ranges if 4 wire connections are used.
The resistance of the connection wires in 2 wire mode will cause an error in the sensor
reading and therefore accuracy is not guaranteed.

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Table A- 155 Noise reduction and update times for the RTD modules

Rejection frequency Integration time Update time (seconds)

selection 4-channel module 8-channel module
400 Hz (2.5 ms) 10 ms 1 4-/2-wire: 0.142 4-/2-wire: 0.285
3-wire: 0.285 3-wire: 0.525
60 Hz (16.6 ms) 16.67 ms 4-/2-wire: 0.222 4-/2-wire: 0.445
3-wire: 0.445 3-wire: 0.845
50 Hz (20 ms) 20 ms 4-/2-wire: 0.262 4-/2-wire: 0.524
3-wire: .505 3-wire: 1.015
10 Hz (100 ms) 100 ms 4-/2-wire: 1.222 4-/2-wire: 2.425
3-wire: 2.445 3-wire: 4.845
1 To maintain module resolution and accuracy when the 400 Hz filter is selected, the integration time is 10 ms. This
selection also rejects 100 Hz and 200 Hz noise.

NOTICE

After power is applied, the module performs internal calibration for the analog-to-digital
converter. During this time the module reports a value of 32767 on each channel until valid
data is available on that channel. Your user program may need to allow for this initialization
time. Because the configuration of the module can vary the length of the initialization time,
you should verify the behavior or the module in your configuration. If required, you can
include logic in your user program to accommodate the initialization time of the module.

Representation of Analog values for RTDs

A representation of the digitized measured value for the RTD standard temperature range
sensors are shown in the tables below.

Table A- 156 Representation of analog values for resistance thermometers PT 100, 200, 500, 1000
and PT 10, 50, 100, 500 GOST (0.003850) standard

Pt x00 Units Pt x00 Units

standard in standard in
°C (1 digit = °F (1 digit =
Decimal Hexadecimal Decimal Hexadecimal Range
0.1° C) 0.1 F)
> 1000.0 32767 7FFF > 1832.0 32767 7FFF Overflow
1000.0 10000 2710 1832.0 18320 4790 Overrange
: : : : : :
850.1 8501 2135 1562.1 15621 3D05
850.0 8500 2134 1562.0 15620 3D04 Rated range
: : : : : :
-200.0 -2000 F830 -328.0 -3280 F330

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A.9 Digital signal boards (SBs)

Pt x00 Units Pt x00 Units

standard in standard in
°C (1 digit = °F (1 digit =
Decimal Hexadecimal Decimal Hexadecimal Range
0.1° C) 0.1 F)
-200.1 -2001 F82F -328.1 -3281 F32F Underrange
: : : : : :
-243.0 -2430 F682 -405.4 -4054 F02A
< -243.0 -32768 8000 < -405.4 -32768 8000 Underflow

A.9 Digital signal boards (SBs)

A.9.1 SB 1221 200 kHz digital input specifications

Table A- 157 General specifications

Technical data SB 1221 DI 4 x 24 VDC, 200 kHz SB 1221 DI 4 x 5 VDC, 200 kHz
Order number 6ES7 221-3BD30-0XB0 6ES7 221-3AD30-0XB0
Dimensions W x H x D (mm) 38 x 62 x 21 38 x 62 x 21
Weight 35 grams 35 grams
Power dissipation 1.5 W 1.0 W
Current consumption (SM Bus) 40 mA 40 mA
Current consumption (24 VDC) 7 mA / input + 20 mA 15 mA / input + 15 mA

Table A- 158 Digital inputs

Technical data SB 1221 DI 4 x 24 VDC, 200 kHz SB 1221 DI 4 x 5 VDC, 200 kHz
Number of inputs 4 4
Type Source Source
Rated voltage 24 VDC at 7 mA, nominal 5 VDC at 15 mA, nominal
Continuous permissible voltage 28.8 VDC 6 VDC
Surge voltage 35 VDC for 0.5 sec. 6V
Logic 1 signal (min.) L+ minus 10 VDC at 2.9 mA L+ minus 2.0 VDC at 5.1 mA
Logic 0 signal (max.) L+ minus 5 VDC at 1.4 mA L+ minus 1.0 VDC at 2.2 mA
HSC clock input rates (max.) Single phase: 200 kHz Single phase: 200 kHz
Quadrature phase: 160 kHz Quadrature phase: 160 kHz
Isolation (field side to logic) 500 VAC for 1 minute 500 VAC for 1 minute
Isolation groups 1 1
Filter times 0.2, 0.4, 0.8, 1.6, 3.2, 6.4, and 12.8 ms; 0.2, 0.4, 0.8, 1.6, 3.2, 6.4, and 12.8 ms;
Selectable in groups of 4 Selectable in groups of 4

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