Communication Guide, ©ComAp – March 2014 32
IGS-NT Communication Guide 03-2014.pdf
Ethernet - MODBUS/TCP (Direct)
Controllers
Hint:
Ethernet Modbus/TCP connection is available for all mentioned controllers via external internet bridge
IB-NT (see the chapter Ethernet – MODBUS (IB-NT)).
Number of clients connected simultaneously
1 client ModBus TCP/IP
Ethernet connection settings
Perform the connection settings the same way as for Single controller Ethernet connection.
Modbus/TCP access code
Every Modbus/TCP session has to be started with writing the access code from the modbus/tcp client
to the controller. If the session is closed and reopened again the access code must be written again.
The session can be closed by the client or the controller closes the session automatically if there is no
activity from the client side for 15s.
- There are new dedicated registers for entering the AccessCode via Modbus/TCP.
- The register numbers are 46339-46346 (register address 6338-6345).
- The previous method using register address 24535 remains working as well.
- Example of the Modbus message is following (in HEX):
01 10 18 C2 00 08 10 30 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 FE F3
01 Controller address
10 Modbus function (16dec – Write multiple registers)
18C2 Register address (18C2hex = 6338dec = register 46339)
0008 Number of registers
10 Length of the data (Number of registers x 2B)
30000000... Access code string (16 chars, null-terminated, ASCII, here “0”)
FEF3 CRC
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