B&B Electronics VFG3000 - Manual - Manual (Page 33)

C ONFIGURING C OMMUNICATIONS S LAVE P ROTOCOLS
R EVISION 1 P AGE 17
For most protocols, this will produce higher performance, as it will allow simultaneous
communications with the two devices. It will, however, consume two of the four protocols,
limiting your ability to connect via additional protocols in complex applications. Your second
option is therefore to use a single protocol configured as a Modbus TCP/IP Master, but to add
a further device so that both slaves are accessed via the same driver…
This will typically produce slightly reduced performance, as Fieldbus Gateway Manager will
poll each device in turn, rather than talking to both devices at the same time. It will, however,
conserve Ethernet protocols, allowing more complex applications without running out of
resources.
S
LAVE
P
ROTOCOLS
For master protocols (ie. those where the Gateway initiates communication) there is no
further configuration required under the Communications icon. For slave protocols (ie. those
where the Gateway receives and responds to remote requests), however, the process is
slightly more complex, as you must also indicate what data you wish to expose for remote
access.
S ELECTING THE P ROTOCOL
As with master protocols, the first stage is to select the protocol for the communications port
that you wish to use. The example below shows the Gateway’s RS-232 port configured for
operation with the Modbus ASCII Slave protocol…