ProSoft Technology MVI56-DFCM - Manual (Page 38)

Ladder Logic MVI56-DFCM ♦ ControlLogix Platform
User Manual DF1 Half/Full Duplex Master/Slave Serial Communication Module
Page 38 of 106 ProSoft Technology, Inc.
September 24, 2014
3.2 Configuration Objects (DFCMCONFIG)
Configuration of the module is performed by filling in the values in the module
object defined in the Controller Tags Edit Tags dialog box. Each parameter
required by the module has a defined location in the object. The tables and
discussions below describe the parameters set in the dialog box. You can view
these tables by opening the data type under the User Defined Data Type option
in the Controller Organization window.
3.2.1 Module Definition (DFCMModule)
Name Data Type Description
WriteStartReg INT Start reg to transfer from PLC to module
WriteRegCnt INT Number of registers to write from PLC
ReadStartReg INT Start reg to transfer from module to PLC
ReadRegCnt INT Number of registers to transfer from module
BPFail INT Determines module operation if BP fails
0=continue,>0=number of retries before comm shutdown
ErrStatPtr INT Internal DB start register for status data (-1=Ignore)
This object defines the parameters for data movement between the module and
the processor. Values entered determine the ladder logic and data size required
in the application. The ReadData and WriteData arrays must be sized to or larger
than the count values entered. The ladder logic must process the number of
blocks of data to be transferred. The number of blocks is computed as follows:
BlockCnt = INT(RegCnt/200) + if(MOD(RegCnt,200), 1,0)
If the register count is evenly divisible by 200, the number of blocks is easy to
compute and the ladder is much simpler to write. If the number is not evenly
divisible by 200, special handling of the last block of data must developed, as it
must transfer less than 200 words. It is recommended that the count values
always be set to values evenly divisible by 200.
The BPFail parameter determines if the module should continue communicating
on the DF1 network when the backplane transfer operation fails. A value of zero
indicates that the module should continue communicating when the backplane is
not operational. If the value is greater than zero, the backplane will be retried the
entered number of times before a failure will be reported and communication will
cease on the ports. When backplane communication is restored, the module will
start communicating on the network. For example, if you enter a value of 10 for
the parameter, the module will stop all DF1 communications if 10 successive
backplane errors are recognized. When a successful transfer is recognized, the
module will resume communications on the network.
The ErrStatPtr parameter defines the location in the module’s database where
the error/status data will be stored. If the value is set to -1, the data will not be
stored in the user data area. A value between 0 and 4939 will cause the
module’s program to store the data at the specified location.