Siemens S7-300 Timers

[Mylo]

Certainly didn't believe that there were Only 128 hardware timers , however for my programming skills or lack thereof, i didn't know how to create suitable timers for my application for the fact that i had utilised a very labourious method of programming while it never failed it was solid. I have tried to utilise the scan cycle to generate my own resolution of times which in itself is ok however when you use possibly over 300 timings for your process and about 50 or more for the control you tend to get a bit bewildered. Well I do anyway.


However don't quite understand how you manage to do it, don't suppose you have a ladder of what you do handy. If you use this method do all your timers have to "Start" at the same time?

Cheeers

 

[Peter Nachtwey]

However don't quite understand how you manage to do it, don't suppose you have a ladder of what you do handy. If you use this method do all your timers have to "Start" at the same time?

Cheeers

No I don't have a an S7 example handy and No, the timers don't need to start at the same time. Maybe latter this evening I can do an S7 example. I am at work now.

First, I doubt you really need 400 timers. I would heed what RSDoran said. However, to make 400 timers I would make a function block that would store all the data for the 400 timers. I would keep the presets and elasped times or start times for all the timers there. An index would be need to access/select one of the 400 timers.
Do you know how to index into an array of 400 times or dwords? That is the only trick. As pointed out before you should also look at using the IEC times because they are easier to work with.

 

[RRobbins]

Hey guys, here is one I already did. It is set up to do 600 timers (300 photo eyes on / off). The Data Block is set up for 500 (1000 timers) photo eyes. You can do as many as you want, as long as the total CPU scan time is less than 100ms. The limit is 100ms because of the time base is 100ms. No builtin timers are used. The code behind the timers is total of 2 networks and is called 300 times per 100ms interrupt. If you want a TP170a or b program for this, I have that so you can set and read the timers, using 7 tags. It is FAST and effecient. If you want to use an HMI, look at the indirect adress function and it allows access with using 7 tags to preset and read the values for the timers. If you still have trouble, drop me an email.