ProSoft Technology MVI56-DFCM - Manual (Page 86)

Reference MVI56-DFCM ♦ ControlLogix Platform
User Manual DF1 Half/Full Duplex Master/Slave Serial Communication Module
Page 86 of 106 ProSoft Technology, Inc.
September 24, 2014
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 DFCM.config.PortX 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.
In order to read the slave status table, ladder logic must be written. The ladder
logic must send a special block to the module to request the data. Each port has
a specific set of blocks to request the data as follows:
Block ID Description
3002 Request for first 128 slave status values for Port 1
3003 Request for last 128 slave status values for Port 1
3102 Request for first 128 slave status values for Port 2
3103 Request for last 128 slave status values for Port 2
The format of these blocks is as shown below:
Offset Description Length
0 3002 to 3003 or 3102 to 3103 1
1 to 247 Spare 246
The module will recognize the request by receiving the special write block code
and respond with a read block with the following format:
Offset Description Length
0 Reserved 1
1 Write Block ID 1
2 to 129 Slave Poll Status Data 128
130 to 248 Spare 119
249 3002 to 3003 or 3102 to 3103 1
Ladder logic can be written to override the value in the slave status table to
disable slaves (state value of 3) by sending a special block of data from the
processor to the slave. Port 1 slaves are disabled using block 3000, and Port 2
slaves are disabled using block 3100. Each block contains the slave node
addresses to disable. The structure of the block is displayed below:
Offset Description Length
0 3000 or 3100 1
1 Number of Slaves in Block 1
2 to 201 Slave indexes 200
202 to 247 Spare 46
The module will respond with a block with the same identification code received
and indicate the number of slaves acted on with the block. The format of this
response block is displayed below: