Dear all,

I know this could be "impossible" or at least "too much imprecise" but I have :

1 D425-2 Scout 4.4 TIA

1 ET200 SP with 7 (seven) encoders that are TTL incremental , 5000 pulses

I have no problems in getting the encoder counting : I see it changing from my Scout program.

My Profinet is set at 2.0 ms

My cycle time of Simotion is set at 9 ms ( I have tried to set it at 6 ms also).

My problem is that in my program I need to

1) When the encoder is starting to count I have to capture the "initial count" and compare it to a final count.

Problem is that the encoder moves very fastly so I detect it in near random positions: one time is 20 pulses, another is 45, another is up to 110 and this gives me troubles for the successive counts and elaboration that I do.

Basically I do this:

IF dwEncPulses>0 and NOT bFirstCountDone THEN

dwInitialCount:=dwEncPulses;

bFirstCountDone:=TRUE;

END_IF

ANd as you see the dwInitialCount that theoretically should be close to 1 or few units, can be higher and higher (up to 100).

I tried to launch this program in Background task, in IPO task , in timed task (9 ms or 6 ms) but without luck.

Is there any trick that I can do to turbofastly detect when my encoder is starting to move ?

Danke in advance

Hi,

What about HW interrupt? See the SIMATIC ET 200SP Manual Collection under chapter "5.2.2 Triggering a hardware interrupt"

I hope I could help!

Jeff Casagrande

Can you put your ET200 is a synch domain?  That way your external Profix is linked to your IPO time.

 More precisely - to the Servo.  Unless they are 1:1

Thanks guys, but I am still puzzled:

ok, consider I can make it synched , so my profinet sends my data (the count of each encoder) at every Servo clock.

I need to manage this position (sorry: count) in a task . Where should I schedule that task ? IPO ? Timed ?

My fear is to risk the IPO saturation time since the program should run seven times sine I have seven encoders...

Maybe there are special stuffs in Simotion that can "capture the position of the encoder" and tell (with a signal or w/e) when that position is "after" a certain range ?

I am thinking about switch cam as vague example

Don't do it in a Motion Task.  Do it in a Servo task.  Just one little program.

Really my ignorance and stubbornance, but I still can't figure out how to use Motion Tasks after all of these years. 

Hi Jeff, perhaps you mean the IPO tasks ?

The problem is that (from my small experience with them) it is pretty easy to send the CPU in stop because the IPO time was overrun, so everytime I am scared to "overcharge" the IPO programs...

In this situation I can use 7 FBs but the basic things doesn't change.

The advantage is that IPO in that situation will be really fast and fast.

Motion Task ? I thought about them but I don't theink they are made for millisecond-reaction routines but, instead, for motion instructions where timings are different.

Ofcourse many programs we make lies in launching capture in a motion task, so this means that motion tasks "can be helpful", but I really don't know how ...

So I am puzzled between :

1) Torturing IPO and risking a potential CPU Stop

or

2) Finding some intelligent command and launch it in a motion task and see if something changes ?

Anyhow I think that everything requires using the Synch mode....

I run lots of programs in IPO or SERVO tasks, depending if they are reference or feedback dependent.

If you go into Task Configuration in the Execution System, you can set the IPO or SERVO ratio as a percent of SERVO or IPO time slice.  Default is usually 25%, but you can go as high as 75%.

Thanks Jeff, that could help.

Today I will speak with our Siemens guru that normally helps us, if we come to an intelligent solution I will post it here...

Hello, just an update, our Siemens conctact said that using the Synced mode can really help but this is possible if you can work with an assigned topology.

In my case I have two switches that are Scalance but basic version, so Sync is not possible :(

And this really cuts every planning, except investigating if there is something in the HWCFG of the TM count board that can automatically do something of useful