Where a third-party server uses the Modbus protocol to retrieve data from ClearSCADA, the ClearSCADA system acts as a Slave PLC.
For this scenario, ClearSCADA needs to run the Modbus Slave driver, and you need to configure suitable Slave items in the ClearSCADA database (see Configuring Modbus Slave Devices in ClearSCADA).
The Modbus Slave indexes into the Value Maps to extract the value(s) that are requested by the third-party server.
