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