The Modbus TCP gateway is capable of being both client and server. As a client, it will poll other Modbus TCP devices. As a server, other Modbus TCP devices may poll i.CanDoIt. The server map even allows i.CanDoIt to mimic another device by replicating its register map.

The remote device "read rule" mainly says what remote register to read and where to put the data. But you have the option of scaling data as it comes in. You also have the option of applying a default value if the read fails.

The remote device "write rule" allows setting up a "send on delta" to only write the register to the remote device when the local data has changed. You can also send periodically, with optional data scaling on the way out.

The server map allows you to effectively relocate registers as seen by an outside Modbus TCP client (master). This allows the AddMe III to replace existing Modbus TCP devices without rewriting the front end software that wants to access the data. If this server map is "exclusive", this means the external client can only see registers listed in this map. If non-exclusive, this map is checked first, but if the requested register is not found, a second check is made to see if it exists in the set of registers already known to AddMe III locally.