Dear sir,

I have an application of high speed counter

I have used the hardware as CPU 1214C , Encoder 24VDC/1024 PPR (A & B channel A is connected to I0.0 & B is connected to I0.1 ) .

Application : Encoder is mounted on a rotating shaft , max RPM of shaft is 200 RPM. One revolution of shaft is equal to one revolution of Encoder. So encoder 1024 pulses = one revolution

We have to actuate an output in every cycle of shaft when the shaft position is in between say 100 to 140 pulses.

For this I have used a HSC1 in which after 1024 pulses the current value becomes 0 by a hardware interrupt OB40 . after every 1024 pulses the count in ID1000 becomes 0.

We have put a mark on shaft & this mark is matched with a stationery mark at the other end for matching the 0 position in the start , after that when we start the Shaft the 0 position comes exactly at the mark ( if shaft rotates slowly say at 50- 75 rpm) but if we rotate the shaft at 120 or more rpm the 0 mark does not come at the matching point the position should be 0 wheras it shows 976 ,980 or 985 ( always behind )

Now the problem is that the 0 position is varying even after 15-20 revolutions & because of this the output is not actuated as per the true position.

As per my observation the hardware interrupt is not working properly . Pl find attached the program backup.

The grounding/ earthing is ok & connected to PLC & Encoder as well.

Pl give a solution by a giving example program.

B/R