These are the codes that mean "ask again later" rather than "your request is
wrong": 5 ACKNOWLEDGE, 6 SERVER_DEVICE_BUSY,
10 GATEWAY_PATH_UNAVAILABLE, 11 GATEWAY_TARGET_DEVICE_FAILED_TO_RESPOND.
Codes such as 1 ILLEGAL_FUNCTION, 2 ILLEGAL_DATA_ADDRESS, and
3 ILLEGAL_DATA_VALUE are deterministic — retrying them only adds bus
traffic and latency.
Modbus exception codes retried by default.
These are the codes that mean "ask again later" rather than "your request is wrong":
5ACKNOWLEDGE,6SERVER_DEVICE_BUSY,10GATEWAY_PATH_UNAVAILABLE,11GATEWAY_TARGET_DEVICE_FAILED_TO_RESPOND.Codes such as
1ILLEGAL_FUNCTION,2ILLEGAL_DATA_ADDRESS, and3ILLEGAL_DATA_VALUE are deterministic — retrying them only adds bus traffic and latency.