Modbus troubleshooting

User manual

In Service View > Communication analysis you can see:
  • Modbus Master RTU port 1
  • Modbus Master RTU port 2
  • Modbus Master TCP/IP
  • TCP/UDP multi mode status
For each selection, you can see configuration and operating details. For example, for Modbus Master TCP/IP you can see:
  • Details for each connected device (use <Prev. and Next> to navigate)
  • IDs, Rx and Tx info, IP address, connected (true or false), and so on.

The Battery/Storage controller controls the ESS with communication to a battery management system (BMS), a battery control unit (BCU), or a power conversion system (PCS).

Exception codes and errors

The Rx status can show the following Modbus exception codes and errors.

Text Reason
ACKNOWLEDGE The Modbus server has accepted the request and is processing it, but a long time is required. This response is returned to prevent a timeout error in the Modbus client.
BYTESEXPECTED ERROR The number of bytes received is wrong.
CLIENT CRC ERROR CRC error in the received telegram.
FUNCTION ID ERROR Wrong function ID in the received telegram
GATEWAY N/A The Modbus gateway configuration is wrong.
GATEWAY TGT NORESP The Modbus server failed to respond.
ILLEGAL DATAADDR The data address(es) of some or all the required entities are not allowed in the Modbus server.
ILLEGAL FUNCTION The function code received in the query is not allowed by the Modbus server.
ILLEGAL_DATAVALUE The value is not accepted by the Modbus server.
NEGATIVE ACK The Modbus server cannot perform the programming functions.
QUERY ERROR The Modbus client could not transmit the telegram.
RESP DATA ERROR The response received did not contain the expected data.
SERVER ADDR ERROR Wrong Modbus server ID in the received telegram.
SERVER BUSY The Modbus server is busy processing a long command. The Modbus client should retry later.
SERVER CRC ERROR The Modbus server detected a CRC error in a received telegram.
SERVER FAILURE An unrecoverable error occurred while the Modbus server was attempting to perform the requested action.
TCP CONNECTION ERROR The TCP/UDP socket could not be connected to the Modbus server. The Modbus server TCP/IP interface may be off. The IP address may be wrong. You may have selected TCP or UDP incorrectly.
TIMED OUT No response.