Code. Select the required access type: Basic, Regular, Extended or Specific. Specific is used to read a single identification object. The other access types limit the range of objects returned.

First Object ID. Enter the ID of the first object to be requested. If you are using the Specific access type, this will be the only object read.

The ID should be in the range 0 to 255. Although not required by the Modbus specification, the ID would normally be restricted to the range 0 to 2 for Basic access, and to the range 0 to 127 for Regular access.