Monitoring The Total On Times - Omron DEVICENET SAFETY - CONFIGURATION MANUAL 05-2005 System Configuration Manual

7-2-5

Monitoring the Total ON Times

Description
A DST1-series Safety I/O Terminal totals the time each safety input contact, test output contact, and safety
output contact is ON, and saves it internally in non-volatile memory. If a cumulative time reaches the thresh-
old value, the Connected Component Maintenance Flag in General Status will turn ON.
• Measurement time: 0 to 4,294,967,295 seconds (stored data: 0000 0000 to FFFF FFFF hex)
• Measurement unit: Seconds
The user can monitor this information using the Network Configurator and explicit messages.
Note: – One contact cannot be used at the same time for both the time and count monitoring functions. Se-
lect only one of these in the Maintenance Counter Mode Choice.
– If the Maintenance Counter Mode Choice is changed, the counter or time data saved internally will
be cleared.
– This function does not operate when the I/O power supply is OFF.
– The time monitor checks if the connected component is ON approximately every second. This
should be noted when the time is measured in increments of 1 second or less.
Measuring 0.5-second ON Time
In Figure A, the actual ON time is 0.5 seconds x 3, or 1.5 seconds. Operation is ON only once when mea-
surements are made, however, so the time is measured as 1 second.
In Figure B, the actual ON time is 0.5 seconds x 3, or 1.5 seconds. Operation is ON twice when measure-
ments are made, however, so the time is measured as 2 seconds.
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Safety I/O Terminal
Total ON time
I/O power
Sensor
Total ON time
Connected
device
Reading taken approximately every second.
ON
OFF
0.5 s
Figure A
Reading taken approximately every second.
ON
OFF
0.5 s
Figure B
Recorded in Slave
Section 7: Monitoring Devices