Modbus channels use either Serial or Modbus TCP communications. In either case, if you have a Simple Modbus scanner on your system that should be, but is not, healthy (online), use the charts within the Troubleshooting section in the Geo SCADA Expert Guide to Simple Drivers to solve the problem (see Troubleshooting in the Geo SCADA Expert Guide to Simple Drivers).
If a scanner uses Modbus TCP to communicate with the Geo SCADA Expert server (with a Communications Type of either Modbus TCP or Modbus RTU), and performing the checks given in CHART 1 within that Troubleshooting section has not solved the problem, see CHART 2: Scanners Using Modbus TCP in this Guide.
When troubleshooting on a Geo SCADA Expert system, check the Events List for diagnostics messages. The messages may help you to identify the cause of any problems.
To display scanner details in List format from the Queries Bar, filter the constraints on the Point Sources List.
For information on analyzing a Geo SCADA Expert system, see System Analysis in the Geo SCADA Expert Guide to the Server Status Tool, and the driver-specific documentation.