The Modbus Statistics dialog shows counter values for all of the Mobus port statistics for the selected SIS controller since the last time it was reset.
If power to the SIS controller is interrupted, all counter values on the Modbus Statistics dialog restart from zero after power is restored and the SIS controller comes out of the reset state. In the event of a switchover to the standby SIS controller of a redundant pair, all counter values on the Modbus Statistics dialog restart from zero.
The Modbus Statistics dialog contains the following values:
- Comm Port Initialization Failure - Incremented whenever any port initialization function fails while creating, initializing, binding or listening to a socket, accepting a connection request, or waiting on an incoming message.
- Comm Port Max Connections Exceeded - Incremented whenever a new connection request occurs after three connections already exist.
- Comm Port Number of Connections - The total number of current connections, from zero to three.
- Comm Port Receive Request Failure - Incremented whenever an error occurs while retrieving an incoming message from the socket.
- Comm Port Receive Request Successful - The total number of messages successfully received by the Modbus application from DeltaV processes.
- Comm Port Send Response Failure - Incremented whenever an error occurs while sending an outgoing message to the socket.
- Comm Port Send Response Successful - The total number of messages successfully sent from the Modbus application to DeltaV processes.
- Modbus Invalid Message Length - Incremented whenever an incoming request specifies a message length that does not match that required by the function code and the configured data.
- Modbus Invalid Number of Registers - Incremented whenever an incoming request specifies a number of registers that exceeds those configured.
- Modbus Invalid Start Address - Incremented whenever an incoming request specifies a start address that does not fall within the range of those configured.
- Modbus Slave Device Busy - Incremented whenever an incoming request cannot be responded to because either a previous request is still being processed or the Modbus process is not ready.
- Modbus Unsupported Function Code - Incremented whenever an incoming request for an unsupported function code occurs.
- Modbus Unsupported Number of Registers - Incremented whenever an incoming request specifies a number of registers that exceeds those permitted by the function code.
- Modbus Unsupported Value Written - Incremented whenever an incoming request specifies an unsupported coil register value other than 0x0000 or 0xFF00.
- Number of Registers Mapped - Indicates the number of registers that have been configured and bound to parameters for the controller with Modbus enabled.