MBS Protocol
PLX30 Series
User Manual
Ethernet and Serial Gateways
Page 126 of 200
ProSoft Technology, Inc.
September 19, 2012
7.1.3 Gateway Internal Database
The internal gateway database is central to the functionality of the gateway. This
database is shared between all the ports on the gateway, permitting data from
devices on one communication network port to be viewed and controlled by
devices on another port or network.
Modbus Port Access to Database
The Multiple slave support in the gateway permits remote Master applications
(HMI software, Quantum processors, etc
) to read from and write to the gateway’s
database.
When configured as a slave, the internal database of the gateway is used as the
source for read requests and the destination for write requests from remote
Masters. Access to the database is controlled by the command type received in
the incoming message from the remote Master. The following table defines the
relationship of the gateway’s internal database to the addresses required in the
incoming Modbus TCP/IP requests.
Database Address
Modbus Address
0
40001 (five-digit addressing) or 400001 (six-digit addressing)
1000
41001 or 410001
2000
42001 or 420001
3000
43001 or 430001
3999
44000 or 440000
