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FAQ


No.484 How can I configure Sollae Systems' Modbus Gateway? 24-09-2020

Sollae Systems' Modbus Gateway is designed to provide protocol conversion between Modbus Serial (RTU/ASCII) and Modbus TCP. Modbus Gateway products can be configured by spFinder, a free-of-charge software provided by Sollae Systems.


Compared with other ezTCP products, besides basic network setting (IP Address, Wireless LAN), there are some advanced working parameters for Modbus Gateway:

Parameters Description
Transmission Mode Set Modbus transmission mode as Modbus RTU or Modbus ASCII. The default is Modbus RTU.
Baudrate (unit: bps) Set a baud rate of serial port. The default is 9,600bps.
Serial Parameter
Data Bits Set number of data bits of serial connection. The default is 8.
Stop Bits Set number of stop bits of serial connection. The default is 1.
Parity Set parity bit of serial connection. The default is None.
Modbus
Query Flow Set direction of Modbus query. You can select TCP to Serial or Serial to TCP.
If you select TCP to Serial, the product operates as a TCP server, and if you select Serial to TCP, the product operates as a TCP client. The default is TCP to Serial. The default is TCP to Serial.
Response Timeout (Unit: ms) Set expiration time for a Modbus query. The default is 500 (milliseconds).
Send Gateway Exception Select to send gateway’s exception data or not. When this value is Enable, gateway sends exception data. The default is Enable.
TCP (TCP0, TCP1, TCP2, TCP3)
Peer Address Set IP address of TCP server to be connected. This setting is valid only if the Modbus Gateway works as a TCP Client (Query Flow is set to "Serial To TCP").
Port Set port number for TCP connection. The default is 502.
Unit ID Set unit ID of Modbus TCP device. The default value is 0.
If this value is non-zero, the product will send only the frames whose unit ID matches this value among the query frames received from the master of the network. In addition, this value is used as unit ID when passing query frame of master received from the serial line to slave. On the other hand, if this value is 0, the product forwards all valid query frames received from the master of the network to the slave. In addition, when passing the master's query frame received from the serial line to the slave, the slave address in the query is used as the unit ID.
Slave Address Set slave address of Modbus RTU/ASCII device. This value can be set from 0 to 247. The default value is 0.
If this value is non-zero, the product will send only the frames whose slave address matches this value among the query frames received from the master of the serial line. In addition, this value is used as slave address when passing query frame of master received from network to slave. On the other hand, if this value is 0, the product forwards all valid query frames received from the master of the serial line to the slave. In addition, when passing the master's query frame received from the network to the slave, the unit ID in the query is used as the slave address..
Advanced
Multiple Connection Enable multiple TCP connections. If this item is set to Disable, only one TCP session (TCP0) can be used. If this item is set to Enable, the rest of TCP sessions (TCP1 to 3) are activated (max. 4 sessions at the same time).
Connection Timeout (Unit: sec) Set expiration time for TCP connection in idle state. The idle state means there is no sent or received data on TCP. The default is 60 (seconds).



Example working cases


1) Connect Modbus Master (TCP) to Modbus Slave (RTU/ASCII)





Configuration note for Modbus Gateway:
- Transmission Mode, Baud rate, Serial: Customer-defined
- Query Flow: TCP to Serial (Modbus Gateway works as a TCP Server)
- Slave address: The same as slave address of the Modbus Slave

1.1) Single Modbus master (TCP), single Modbus slave (RTU/ASCII)





1.2) Single Modbus master (TCP), multiple Modbus slaves (RTU/ASCII)





1.3) Multiple Modbus masters (TCP), single Modbus slave (RTU/ASCII)





1.4) Multiple Modbus masters (TCP), multiple Modbus slaves (RTU/ASCII)





2) Connect Modbus Master (RTU/ASCII) to Modbus Slave (TCP)




Configuration note for Modbus Gateway:
- Transmission Mode, Baud rate, Serial: Customer-defined
- Query Flow: Serial to TCP (Modbus Gateway works as a TCP Client)
- Slave address: The same as unit ID of the Modbus Slave (TCP)

2.1) Single Modbus master (RTU/ASCII), single Modbus slave (TCP)





2.1) Single Modbus master (RTU/ASCII), multiple Modbus slaves (TCP)






3) Serial Tunneling - Connect Modbus serial devices (RTU/ASCII) via network





Configuration note for Modbus Gateway:
- Transmission Mode, Baud rate, Serial: Customer-defined
- Query Flow: One Modbus Gateway as a TCP Server and the other as a TCP Client
+ Modbus Gateway on the Master side: Serial to TCP
+ Modbus Gateway on the Slave side: TCP to Serial
- Slave address: The same as slave address of the Modbus Slave (RTU/ASCII)







- See also

- Related Products


[ Modbus Gateway ] SMG-5400, SMG-5410, SMG-5420