Reference MVI56-MCM
♦
ControlLogix Platform
Modbus Communication Module
ProSoft Technology, Inc.
Page 93 of 159
July 24, 2008
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Transferring the Command Error List to the Processor
You can transfer the command error list to the processor from the module
database. To place the table in the database, set the Command Error Pointer
parameter to the database location desired.
To transfer this table to the processor, make sure that the Command Error table
is in the database area covered by the Read Data.
8.2.9 Slave Status Blocks
Slave status blocks send status information of each slave device on a master
port. Slaves attached to the master port can have one of the following states:
0
The slave is inactive and not defined in the command list for the master port.
1
The slave is actively being polled or controlled by the master port. This does not
indicate that the slave has responded to this message.
2
The master port has failed to communicate with the slave device. Communications
with the slave is suspended for a user defined period based on the scanning of the
command list.
3
Communications with the slave has been disabled by the ladder logic. No
communication will occur with the slave until this state is cleared by the ladder
logic.
Slaves are defined to the system when the module initializes the master
command list. Each slave defined will be set to a state of one in this initial step. If
the master port fails to communicate with a slave device (retry count expired on a
command), the master will set the state of the slave to a value of 2 in the status
table. This suspends communication with the slave device for a user specified
scan count (
ErrorDelayCntr
value in the
MCMPort
object for each port). Each
time a command in the list is scanned that has the address of a suspended
slave, the delay counter value will be decremented. When the value reaches
zero, the slave state will be set to one. This will enable polling of the slave.
