Pilz PSS SB HYD, Basic license - Manual (Page 60)

5-12
MBS Basics
Modular Block System: Hydraulic Presses
Assignment of input and output parameters
Input and output parameters should be assigned in accordance with the
details given in the operating manual.
WARNING!
If several unused output parameters are connected to the same flag,
malfunctions may occur in the standard function blocks. If an unused
output has to be assigned a flag, make sure the output is assigned to a
flag that is not used anywhere else in the program.
Minimum scan time
Most of the timer functions required within the blocks are performed using
cycle counters. This means that almost all the timers are available for use
in applications.
WARNING!
• If MBS blocks are used, a minimum scan time must always be
entered in the configurator. Empirical values should be used.
The empirical value can be determined by reading the maximum
program processing time values from DB000:
DB000 DW10 -> max. scan time of FS section
DB000 DW12 -> max. scan time of ST section
The sum of these values plus 10 ms for the operating system test times
plus a tolerance time of 1 ... 5 ms, for example, will provide an initial
value for the “Minimum scan time”. Once the program is loaded, special
monitoring of the “Minimum scan time” is automatically activated in the
CPU. This will put the FS section into STOP (with the error display F-20/
06) if the “Minimum scan time” is exceeded several times. With this
particular STOP, the error message will read: “F-0C/04 Minimum scan
time exceeded too often”. The value for the “Minimum scan time” will
therefore need to be increased. This automatic monitoring is
implemented from the “CPU3” generation, with operating system version
V39. On earlier versions the FS section does not stop, but the error
message F20/06 does appear.