Standard functions
SIMOCODE pro
10-24 GWA 4NEB 631 6050-22 DS 03
10.9 Watchdog (Bus monitoring, PLC/PCS monitoring)
Description
The "Watchdog" function block monitors communication with the PLC via
PROFIBUS DP, as well as the operating state of the PLC in the "Remote"
operating mode.
Schematic
Bus monitoring:
With this type of monitoring, the "Trip - Bus" fault is generated if
• "Bus monitoring" is active
• When, in the "Remote" operating mode (mode selector S1=1 and S2=1), the
Cyclic Data transfer between the PLC and SIMOCODE pro is interrupted, e.g.
by the PROFIBUS DP connection being interrupted.
• "Status - Bus o.k." can always be evaluated. If SIMOCODE pro is cyclically
exchanging data with the PLC,
"Status - Bus o.k." is set to "1".
PLC/PCS monitoring:
With this type of monitoring, "Trip - PLC/PCS" is generated if
• "PLC/PCS monitoring" is activated.
• The PROFIBUS DP switches to the "CLEAR" status when in the "Remote"
operating mode (mode selector S1=1 and S2=1).
• The "Status - PLC/PCS in Run" can always be evaluated. If the PROFIBUS DP
is in the "CLEAR" status, the "Status - PLC/PCS in Run" is set to "0".
If the "PLC/PCS monitoring - Input" is connected primarily to the "Cyclic
Receive - Bit 0.7" bit, the status of the PLC is deduced from this bit only.
Fig. 10-13: "Watchdog (PLC/PCS Monitoring)" function block
Notice
"Bus monitoring" and "PLC/PCS monitoring" can only be effective if the DP
slave address monitoring is activated in the DP master system.
PLC/PCS monitoring - Input
Trip - PLC/PCS
Watchdog (PLC/PCS monitoring)
Bus/PLC fault - Reset
Bus monitoring
Cyclic communication
Status - PLC/PCS in Run
(level sensitive)
PLC/PCS monitoring
Status - Bus o.k. (Bus is active)
Trip - Bus
Bus response
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