ProSoft MVI56E-MCMR User Manual page 163

MVI56E-MCMR ♦ ControlLogix Platform
Modbus Communication Module with Reduced Data Block
Block Response from Module to Processor
Word Offset
0
1
2 to 39
The following illustration shows the MSG instruction configuration for a block of
this type.
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Data Field(s) Description
Number of Slaves This field always receives a value of 248 (-8 as a
to report signed SINT, 16#F8). A status word for all potential
Modbus Slave Device Addresses will be included in
the returned data.
Start index of first This field is always 0. All 248 potential Modbus Slave
Slave
Device Addresses will have a corresponding Status
Word in the returned data.
Slave Status List
0
data
1
2
The Slave is inactive, not currently the slave
being actively polled, waiting for its turn to be
polled, or not a Modbus Slave Device Address
used in the Command List for the Master port.
The Slave at this specific address is the one
currently being polled or controlled by the
Master port. This does not indicate that the
Slave has responded to a poll request; only
that the Master is currently trying to poll this
Slave.
The may be thought of as a "Slow Poll" mode,
whereby a Slave with communications errors
will be polled at a lower-than-normal
frequency. This status is set by the Master
port whenever it has failed to communicate
with the Slave device and the Port
configuration parameter, E
C , has been set greater than 0.
OUNTER
Reference
User Manual
D
RROR ELAY
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