Chromperfect modules have PLC-like powers.
For the most part, they are MODBUS masters which communicate with Acromag devices, which are MODBUS slaves.
It happened that one of these modules was required to make report data available to a PLC via MODBUS. However, this could not be done directly, since the customer's existing PLC could not receive MODBUS messages because it acted only as a master, not a slave. For this reason, an intermediate repository was necessary. This is a MODBUS slave device, which stores the data generated by the Chromperfect modules and makes it available to the PLC.