Siemens IEC timer maximum time

radfahrer

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Tried Googling and searching this forum for the answer to this, but no luck, so figured start a new post to see if anyone can help me...or confirm my calcs.



Question is what is the maximum length for a timer you can track with a Siemens IEC timer. From what I understand, it uses a DINT for the preset in milliseconds.
If that's an unsigned DINT then it would be 2^32/3,600,000 or ~1193 hours (49 days). If it's a signed DINT then would be half of that.



Have an application looking to do several days of timing, and want to see if I need to go to using 1 sec timer with counters or if the IEC will work as is.


-G
 
radfahrer said:
Tried Googling and searching this forum for the answer to this, but no luck, so figured start a new post to see if anyone can help me...or confirm my calcs.



Question is what is the maximum length for a timer you can track with a Siemens IEC timer. From what I understand, it uses a DINT for the preset in milliseconds.
If that's an unsigned DINT then it would be 2^32/3,600,000 or ~1193 hours (49 days). If it's a signed DINT then would be half of that.


Have an application looking to do several days of timing, and want to see if I need to go to using 1 sec timer with counters or if the IEC will work as is.

-G
Click to expand...

It is somewhere around 24Day20H which is still accepted to PT

(Time is signed Dint, so it is around 24,855 days)
 
When I see a field and it doesn't tell me the range, I'll enter a really big number and when I try to accept/enter many software packages will tell you it is invalid and show what the valid range is.

And while the timer can time that long, you might consider the readability of the value. If I see 1.3 billion milliseconds have passed, I'll have to do the math to get that to a usable number. You might add logic to do that if operators need to see that as meaningful data.

OG
 
Fun fact, if you need to go bigger (or smaller) the 1500 also supports the LTIME data type for timers, which counts in nanoseconds and goes up to 106751 days. I won't live long enough to see an LTIME timer overflow, so that's PROBABLY big enough for the foreseeable future.
 
You could use the dtl data type and the 'Date and Time of Day' commands in Extended Instructions instead of an IEC Timer.

dtl data type.JPG
 
What if PLC reboots between timing.

IEC timer would go zero if input goes to 0.

Would it be better to program with ADD block, so it would keep last value?
 

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