If your modbus serial port and its commands are both enabled, but the commands do not appear to even be executing (status shows no requests are being made, data analyzer shows nothing coming out of the port, etc.) check the value of Command Control Reg. Command Control Reg is located in the port settings and is a special override that allows you to control when your commands execute. If you are not intending to use this feature, but the Command Control Reg value is set to anything but -1, change the value to -1 to disable this feature, and download the updated configuration. Without the CCR to override your commands, you should see them begin to execute as intended.
As always, if this does not fix your issue, call or email your region's Prosoft Technical Support for further troubleshooting assistance.