User manual

Module Configuration PTQ-104S Rev2 ♦ Quantum Platform
User Manual IEC 60870-5-104 Server for Quantum
Page 78 of 195 ProSoft Technology, Inc.
February 22, 2013
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 Client
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 data value to the Client as valid.
To properly use data validity checking with a ProTalk rack-mounted module for
Modicon Quantum processor systems, the logic application running in the
processor that communicates to the module through a backplane input/output
driver must be programmed to provide data validity information, as well as the
actual data to be transferred. This logic 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 or the logic 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. In cases where ProTalk modules are used,
backplane communication happens so quickly that cyclic setting of the IV Bits will
be quickly undone by data transfers from processor memory. However, if the
process logic or other protocol application does not clear the IV Bits set by
firmware, all IEC database monitor point values will be reported to the Client 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 Client will always be reported as valid data. If
you wish to have actual data validity information relayed to the Client, 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 (page 163).
5.6.24 IV Check Delay Time
1 to 65535 seconds, or 0 to disable Invalid Bit Monitoring
This parameter sets the number of seconds between IV Bit value checks. Every
IEC database monitor point which has an IV Bit address set greater than 0 will
have that bit address checked at the interval specified by this parameter.
Setting this parameter to zero (0) will disable data validity checking.