9. Modbus server

In addition to its normal use as a SNMP-Modbus converter, ModSnmp can simultaneously operate as a Modbus bridge. This means that it can act as a Modbus TCP server/slave, receiving requests from Modbus clients/masters and responding to these requests with data obtained from the Modbus devices.

Ordinary Modbus read and write requests (function codes 1, 2, 3, 4, 5, 6, 15 and 16) will cache data when possible. Other Modbus requests will simply be forwarded to the device, and the device's response will be returned to the Modbus client/master.

The slave IDs (unit identifiers) used by the Modbus server to identify the devices are not the same as the slave IDs configured in the devices themselves (since multiple devices may have the same slave ID if they are on different interfaces). The Modbus client/master should use slave ID 1 to refer to the first configured device, slave ID 2 to refer to the second configured device, and so on. If more than 254 devices have been configured, only the first 254 will be accessible via the Modbus server.

The Modbus Server page enables you to configure the Modbus server:

Copyright © 2019 Wingpath Limited