SGS uses a mapping

database to define which Modbus data points are to

be exchanged between the Modbus Transfer Tables

and the Harmony function block in the controller’s

configuration. Harmony function blocks typically

contain more information than an equivalent Mod

bus point can support, making it necessary to map

more than one Modbus point to a single Harmony

function block. SGS employs the use of multi-map

ping to allow quality, alarms and values to be fully

defined within the ModbusTCP configuration.

On the ModbusTCP network, connections between

client and server devices are made through TCP

sockets. Depending on the module being used, SGS

can be configured to a maximum of 8 server connec

tions to foreign Modbus clients and 128 client con

nections to foreign Modbus servers.