Moxa Technologies NPort 6110 - Manual (Page 32)

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when Auto Slave Unit ID is “Disabled.”
2. When the Modbus serial protocol is set to Modbus/RTU, each message
packet is determined by a character timeout. An incorrect character timeout
might cause a CRC checksum error. NPort Modbus Gateway allows a
variable character time out setting, ranging from 10 to 3000 ms, when the
attached serial device is set to Modbus/RTU.
3. This setting is in effect when the Modbus Gateway connects a Modbus/TCP
Master with Modbus serial slave devices. When the Modbus Gateway can’t
get a response from Modbus serial devices, the Modbus serial protocol will
not respond to the master device. However, the TCP protocol has a longer
waiting time, which could cause a network traffic problem for Modbus/TCP.
For this reason, Modbus Gateway can automatically send a Modbus
Exception Code 16 to the Modbus/TCP master device when there is no
response from the Modbus serial slave devices, making overall network
communication much more efficient.
Yes: default.
No: No Modbus/TCP exception handling.