Using a 1734-IK with a BEI Incremental Encoder.Not counting with Motor running

Cydog

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Good Afternoon ,

I'm using a Compactlogix 1769-L18 , with a 1734-IK , and a BEI Incremental Encoder . I'm able to get the encoder to count , if I rotate by hand , but when I run a 1725 rpm motor at 30 HZ , I don't recieve any counts in my "Present Data " .

FYI , the BEI Incremental Encoder is 5-15 vdc , the 1734-IK is rated for 15-24 vdc and my power supply is set to 15.3 volts.

I run it as low has 5 HZ and it still does not want to count. What do you think would be the issue ?

Thanks in advance ,
 
Make sure the encoder is configured (typically via DIP switches) to a pulse resolution low enough for the module to count.
5 pulses per revolution versus 10000 pulses per revolution will yield different results
 
Get a scope or meter on the inputs themselves and see what the signal voltage is. The BEI encoder might accept up to 15 volts for power, but only have a driver section that outputs 5 volts.

The Installation Instructions for the encoder module say that the ON-state threshold for the 1734-IK is 12.5 volts.

http://literature.rockwellautomation.com/idc/groups/literature/documents/in/1734-in005_-en-e.pdf

Check the filter values as well; the default filter is 50 Hz. It's a low-pass filter, so at 50 Hz it won't show you any faster pulse rates.
 
Last edited:
I remember you asking about encoder input modules and describing a 40:1 reduction ratio on the output of your VFD-driven motor.

Please post info about whether your encoder is mounted on the shaft of your motor, or downstream of the gear reducer, and how many pulses/revolution the encoder is configured or selected to produce.
 
Thanks Ken ,

"Get a scope or meter on the inputs themselves and see what the signal voltage is. The BEI encoder might accept up to 15 volts for power, but only have a driver section that outputs 5 volts."

I think your on to something about this . I think I selected the 1734-IK by mistake. I may need the 1734-IJ instead .
 
Some encoders always put out the same voltage as the supply, so you can feed them 5V or 12V or 24V and get the same output.

But some, especially if the output is meant to be a TTL (5V) output, will accept a range of supply voltages that they run through a regulator.

5-15V supply range would work well on a nominal 12V battery-powered system, for example; it would see 14+ volts during charging, and 11-ish during discharge. But the output would be at a regulated TTL level of 5V if that's how the output circuit is built.

In my opinion you need to know the actual output voltage, so you can make a decision.

Even an ordinary voltmeter will help for diagnostics; even though it will average the voltages while the motor is spinning, if you just connect the meter and bump the shaft a little you should see a 0V or a +X volt signal.
 
Many encoders (BEI included) have open collector outputs which will require you to have pull-up resistors at the reader's inputs. What is your encoder's exact part number? BEI encoders are available in line-driver or NPN open collector outputs and the part number will indicate which one and at what voltage.
 
BEI HS25F-62-R10-BS-1024-ABZC-15V/V-SM12-S

15V/V: Multi-voltage Line Driver (4469*): 100 mA source/sink. Input voltage 5 to
15 VDC +/- 5% standard (Note: Vout = Vin). TTL compatible when used with 5
volt supply.

The encoder is a line driver, no need for pull up resistor, since the Vin = 15,3V the Vou will be the same 15,3V.

bellow a link for the technical documentation of the encoder
http://www.beisensors.com/pdfs/hs25-optical-incremental-encoder.pdf

and also :
Using a Point I/O 1734-IK as an Encoder
597307
Access Level: Everyon
https://rockwellautomation.custhelp.com/app/answers/detail/a_id/597307
 
Good Morning ,

I just got back on this project. Thank you all for your suggestions. I did change the RPI to 20.0 ms and selected No Filter. Seems to be counting well.

Another question I have is , I know I can use the rollover in properties , but how can I use a input or prox , to move a zero into this present data ?

For example , I have this transport chain , and I have three things to do within this 3 foot travel distance , I want to use 3 LIM , instructions that if the encoder counts are within these limits I make something happen , then when the cycle is finished , I want a prox , or internal bit to move a 0 in the present data. I tried that , but when I remove the 0 move condition , it goes right back to , let's say 45,000 , when I made the MOV 0 into Present Data.

What is the best way to do that ?

Thanks so much in advance ,
 
The .PresentData value is always an Input value; you can't write to it (or if you do, it will be written over 20 ms later)

Instead, look at the Output connection. There should be BOOL elements for Counter Reset, Counter Preset, and Value Reset.

If you need to reset the value while the chain is moving, it might be better to connect your reset sensor directly to the Z channel sensor and set up the module for a mode that resets based on a Z pulse.

But if you'll be stopped and just want to program a reset, I think you just have to assert a true condition on the .ValueReset bit.
 
Thanks Ken ,

That worked great . But my encoder is counting down instead of up , for the needed direction. I swapped A and A_ , B and B_ , and Z and Z _ , but it still wants to count down . I also checked Invert Input Z , in properties ( Counter Config ) , and it still counts backwards .

Thanks for your help ,
 
Encoder systems determine direction based on "phase offset"; this is the principle behind a "quadrature" encoder where the inputs are offset by half a pulse width.

If you have an encoder that's counting the reverse of the direction you expect, you always swap Channel A and B.
 

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