In the relay, it is possible to activate one protocol instance, represented by a function block in the relay configuration. The function block is named MBMLPRT1. The function block is present in the configuration by default when Modbus master protocol is available in the relay’s order license; its setting and monitoring parameters are visible in the HMI.
First setup and configuration upload
Dragging the protocol instance function block into the relay configuration is only the first step of the protocol activation. When the protocol instance is added for the first time, it is inactive and unconfigured by default, meaning that it has not been assigned to a physical link port. Neither has any Modbus slave data point configuration been loaded for the instance. Next step is to do these setups.
When a configuration containing the Modbus Master instance is uploaded to the relay, the Operation setting is "Off". After the upload is done, the Modbus Master instance restarts, still with Operation being in "Off" state. Thereafter, Parameter Setting in PCM600 uploads the new settings to all applications, including the Operation "On" values for the protocol instance. In this case the relay must be restarted once more for the Modbus Master protocol to start operating properly.