How to configuration for SCADA communication
September 11, 2019
PREPARATION
1. PC Tool
It can be used at the local site. In order to use it at local, you have to connect PC tool with
Modbus protocol to the front communication port of FTU without modem. It is null modem
cable is required.
2. SCADA interface
FTU has 3 interface for SCADA communication.
① RS232C with modem control (It is default SCADA port)
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② RS232C /485 (Reserved port)
This port can be selected for SCADA interface instead of ‘RS232C’.
If you use for this port, change to ‘RS232C/485’ on below parameter.
③ Ethernet (TCP/IP)
When using for Ethernet communication, change the TCP/IP settings according to your
Ethernet communication network.
3. FTU setting
FTU parameters can be changed through PC tool or the buttons on the front panel of it.
The follow picture shows the communication parameters related to SCADA port. In the
picture, you can change the slave address and remote protocol as you like.
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The picture below is an example of a DNP network using serial and Ethernet.
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TROUBLESHOOTING TIPS
☞ Check cable connection
☞ Check Baud rate, Slave address
* If you change the baud rate of FTU, FTU should be restarted (Power ON Reset).
☞ Check Modem control signal
* FTU SCADA Comm. port use the RTS/CTS flow control. If you don’t want to use the RTS/CTS
flow control, you have to change setting from USED to NOT USED as following picture.
CTS should be inactive state before FTU tries to transmit data. And when FTU tries to transmit data,
it asserts RTS signal to the modem as active. Then the modem should respond CTS signal as active
within “CTS checkout time” (FTU comm. parameter). If FTU receives the CTS active, it transmits
the data, and asserts the RTS as inactive after completes the transmission.
Rx
Tx
RTS Off dly time
RTS
CTS
<Normal transmission sequence>
Rx
Tx
RTS
CTS Checkout time
CTS
<Modem doesn’t respond CTS to the RTS>
The above modem control sequence can be checked by looking at RX, TX and RTS LEDs on the
front panel of FTU.
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☞ Modem control signal sequence during communication using dial-up modem.
Rx
Tx
RTS Off dly time
RTS
CTS
DTR Always active
DSR
Off-hook (Modem On-Line) On-hook (Modem Off-Line)
☞ Use the protocol monitor built-in FTU using PC Tool.
The monitor shows the line traffic data & modem signal change. But the purpose of use is limited to
the check of data handshaking between two stations. It can’t trace the real-time traffic at the
condition which two stations communicate with each other in more frequent than the data dump
display to the protocol monitor window because of the trace buffer overflow.
☞ Use the serial monitor PC program to check the communication traffic in the PC at the
environment which PC Tool communicates with FTU.
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