ProSoft Technology MVI46-DNP - Manual (Page 77)

Reference MVI46-DNP ♦ SLC Platform
Master/Slave Communication Module
ProSoft Technology, Inc. Page 77 of 143
August 23, 2007
If the command control code (M0: .80) passed in the block is valid, the module
performs the requested operation. In processing the requested function, the
module first sets the command control processing bit (I1: /2) to inform the ladder
logic that the event is being processed. When the function is completed by the
module, the return data to the function will be placed in the M0: file, the
command complete bit will be set (I1: /3) and the command control processing bit
(I1: /2) will be cleared. The ladder logic should be programmed to handle the
response message.
The command control functions processed by the module are described in the
following topics:
249 or 9949 – Read Slave Communication Error Table (Master Port)
If the SLC sends a command control code of 249 or 9949, the module responds
with a slave communication error listing. The module can be set up for 100
slaves on its DNP master port. A 10-word data area is established in the module
for each slave. This requires 1000 words of data storage. The following table
defines the data stored for each slave.
Index Parameter Description
0 Index This value corresponds to the index in the device array for the slave.
1 Slave Addr This value corresponds to the DNP slave address for the device.
2 Bad CRC This value represents the number of bad CRC values received from
the slave device.
3 Buff Ovrflw This value represents the number of buffer overflow messages
received from the slave device.
4 Tran Seq# This value represents the number of incorrect transport layer
sequence number errors.
5 Conf Retry This value represents the number of data link layer confirm request
retries.
6 Conf Fail This value represents the number of data link layer confirm request
failures.
7 No App Rsp This value represents the number of application layer no responses
to requests.
8 Spare Reserved for future use.
9 Spare Reserved for future use.
These data values are updated after each command processed by the module.
The command control function 249 (or 9949) is structured to retrieve data for up
to six slave units. The format of the command control block sent from the SLC is
shown in the following table.
Word Offset in Block Data Fields Description
M0: .80 Command Code This field contains the value of 249 identifying the slave
communication error table request.
M0: .81 Number of slaves This field contains the number of slaves to report in the response
message. The value has a range of 1 to 6.
M0: .82 Start Slave Index This parameter sets the index in the slave array where to start. The
first slave in the array has a value of 0 and is the broadcast slave.
The first user defined slave has an index of one. The last index in the
array has a value of MaxSlaves.