B&B Electronics Vlinx MESR9xx - Manual (Page 40)

7. Application Examples Vlinx MESR9xx Modbus Gateway
Page 36 Manual Documentation Number MESR9xx-4508m
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From Serial Masters To Ethernet Master, Slave IDs Fixed
Legacy Modbus slaves may have fixed IDs. To integrate these into a Modbus TCP
network, a multiport MESR model
(List here) can assign virtual slave IDs. For
information on virtual slave IDs, see (list reference) :
Figure 25. Scada to Slaves, IDs Fixed
Keep Serial Master, Add Ethernet Master(s)
In this scenario, the control system is a direct, time-critical serial system. The serial
master must not be replaced, but Ethernet masters will need to have access to the serial
slaves for monitoring or supervision.
Figure 26. Time Critical Control System
A sophisticated Modbus gateway (MESR921 or MESR922) can connect to the devices,
with slaves going to one link and master another. The gateway allows communication
between slaves and master, with a redirector aspect that lets the serial master keep on
communicating with the slaves.