Larger than expected delay between Modbus commands
Posted: Tue Nov 13, 2018 7:38 am
Hi Ben,
I am using the Modbus master component to communicate with a slave i/o device. The component functions appear to work fine with the data being sent and received as expected. However from when one command is sent to the module to another being sent, there is a larger than expected delay.
I am aware of the delay created by the "silent interval" but it also seems that the "UART receive timeout" and the "timeout count" are also contributing to this delay. With the "UART receive timeout" set to 220 mS and the "timeout count" set to 2, there is a 1 second delay from receiving the data until the next command is sent out. Reducing the timeout and the timeout counts, the delay decreases.
Looking at the screen shot there is only approximately 6mS delay between the last of the data being received by the slave module until its response is sent to the master. Since the master is being sent back a response, the timeout delay should not run its full length, but it looks like it is.
The green is the transmitted data to the slave and the blue is the received data from the slave
Any help with this would be most appreciated.
Thanks
I am using the Modbus master component to communicate with a slave i/o device. The component functions appear to work fine with the data being sent and received as expected. However from when one command is sent to the module to another being sent, there is a larger than expected delay.
I am aware of the delay created by the "silent interval" but it also seems that the "UART receive timeout" and the "timeout count" are also contributing to this delay. With the "UART receive timeout" set to 220 mS and the "timeout count" set to 2, there is a 1 second delay from receiving the data until the next command is sent out. Reducing the timeout and the timeout counts, the delay decreases.
Looking at the screen shot there is only approximately 6mS delay between the last of the data being received by the slave module until its response is sent to the master. Since the master is being sent back a response, the timeout delay should not run its full length, but it looks like it is.
The green is the transmitted data to the slave and the blue is the received data from the slave
Any help with this would be most appreciated.
Thanks