ProSoft Technology MVI56-101S - Manual (Page 45)

MVI56-101S ♦ ControlLogix Platform Configuring the MVI56-101S Module
IEC 60870-5-101 Slave Communication Module User Manual
ProSoft Technology, Inc. Page 45 of 193
August 2, 2011
The module will automatically set ON (set to one) the IV Bits of all IEC database
Monitor Points (M_xx_xx point) that have been configured to use invalid bit
monitoring. This means that all IEC database Monitor Points configured with IV
Bit addresses greater than zero (0) will have their IV Bit addresses in the module
database set to a value of one (1) by the module firmware in a timed, periodic
cycle, based on the number of seconds entered in Cyclic Set IV Time.
The IV Bits are checked at the interval specified by the IV Check Delay Time
parameter. At the end of each check delay interval, if an IV Bit for any IEC
database point is ON, an IV Bit Check Fail accumulator for that point will be
incremented. If the value in any IV Bit Check Fail accumulator becomes equal to
the value of the IV Fail Count parameter, the module will consider the data value
of that point invalid and will report the invalid status of that point to the Master
along with the data value.
If the IV Bit is cleared (reset, set OFF, set to zero) before the IV Bit Check Fail
accumulator value becomes equal to the value of the IV Fail Count parameter,
the IV Bit Check Fail accumulator will be reset to 0. The module will consider the
data value of that point valid and will report the valid status of that point to the
Master along with data value.
To properly use data validity checking with a ProLinx Gateway, the application
that communicates to the gateway through the other gateway protocol (Modbus,
EtherNet/IP, etc.) must be programmed to provide data validity information, as
well as the actual data to be transferred. This other application must write bit
values of zero (0) or one (1) to the proper module database addresses along with
the data for each IEC database point.
This means the other protocol application will be responsible for clearing the IV
Bits for data points which contain valid data at a time interval less than the
amount of time required to accumulate the required number of IV Bit Check
failures. If the other protocol application does not clear the IV Bits, then those
IEC database monitor point values will be reported to the Master as invalid.
NOTE: If one or more of the Cyclic Set IV Time, the IV Check Delay Time, or the IV Fail Count
parameters are set to zero, the data validity checking feature will be disabled for all points in the
IEC database and the data reported to the remote Master will always be reported as valid data. If
you wish to have actual data validity information relayed to the Master, be sure the Cyclic Set IV
Time, the IV Check Delay Time, and the IV Fail Count parameters are set to non-zero values and
be sure the application has been programmed to properly manipulate the IV Bit addresses in the
module database. Once data validity checking has been enabled, you can still turn off validity
checking on a point-by-point basis by setting the IV Bit Address to zero (0) for any point you wish to
exclude from data validity checking and reporting.
For more information on the data validity features of this protocol implementation,
refer to Invalid Bit Monitoring.