When using Modbus TCP transport with keep-alive method, the** slave must be connected to the network at the time of enabling the data source**, otherwise communication will not be restored once you connect the slave (until doing a manual data source disabling/enabling cycle).
If there is communication with the slave before enabling the data source, then communication will be atomatically recovered after any connection failure.
This problem is not seen when using simple TCP transport (without keep-alive).
