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SuriSarat

Micrologix 1400 HSC seems to miss pulse

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I am using the HSC0 of the ML1400. 

Using an hengstler incremental encoder RI58-O/2000EK-42KD 2000 PPR.  Need this encoder to ascertain the position of the Wheel rotating. I am using a Proximity sensor, rotating the wheel at slow speed and finding the 0 / 360 degree position of the wheel. When the prox. sensor is sensed, I move 0 the ACC

Tbe encoder has A, B ,N and I have wired A,B to the PLC. 

I want to determine the degree of the wheel rotation. All seemed to be working fine for 3 days. Suddenly we feel the encoder is missing pulses.

Following is the settings of the HSC 

PFN 3, UIE 1, FE 1, AS 1, CE 1, SP 1, UFM 1, OFM 1, OFI 1, UF 1, OF 1, MD 1, CD 1, CU 1, MOD 3, HIP 2000, LOW 0,  OVF 2000, UNF 0 

I AM USING THE INTERRUPT (PFN 3) to count the encoder revolution (cycle) by incrementing a integer variable. 

How I feel that we are missing pulses as follows

1. We are using the encoder position (angle 2000 pulse = 360 degres, 1 pulse = 360/2000 (0.18).  

2. Based on angle we use a solenoid to blow air. This works well for a few cycles and then the angle changes.

To verify, I used the proximity sensor input to verify the HSC Accumulator as follows

if the proximity sensor is on and if the HSC 0 ACC < 1950 add 1 to a variable (This add is just to track ) 

After around 60 revolutions, the value in the variable starts accumulating. 

 

Now my query is :

Should I use MOD 4 as it is two wire. If I use the N channel the encoder resets erratically (probably my configuration of the HSC is wrong)

I feel I am making a mistake in the configuratoin above. Can someone please help and through some light.

Thanks

 

 

 

 

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