1734-IJ Rate Measurement Issue

xshinsoo

Member
Join Date
Jun 2021
Location
Chicago
Posts
1
Hi,

I have the 1734-IJ 5V DC Module connected to my allen bradley PLC.

My current hardware outputs a 5V DC Square wave and I want to read the frequency.

My current settings are as followed:

Type - Rate Measurement
Frequency Precision - X1
Gate Multiplier - 1
Time Base - 250 ms
Filter - 50kHz
Filter A - Checked
Filter B - Checked
Filter Z - Checked

When I output a 40kHz square wave signal into the A, the PLC reads PresentData reads ~19kHz, which is wrong

I did confirm with a DMM that the source is outputting 40kHz, it is just the 1734-IJ is not reading it properly...

If I change my output to say 30kHz, the PLC reads ~30kHz, which is correct.

It would appear to be read wrong whenever I go beyond 38kHz

Now if I chose to pick "No Filter", I can read 40kHz but the precision is not what I want...

What am I doing wrong? And is there anything I can do to improve the precision?
 
Hi,

I have the 1734-IJ 5V DC Module connected to my allen bradley PLC.

My current hardware outputs a 5V DC Square wave and I want to read the frequency.

My current settings are as followed:

Type - Rate Measurement
Frequency Precision - X1
Gate Multiplier - 1
Time Base - 250 ms
Filter - 50kHz
Filter A - Checked
Filter B - Checked
Filter Z - Checked

When I output a 40kHz square wave signal into the A, the PLC reads PresentData reads ~19kHz, which is wrong

I did confirm with a DMM that the source is outputting 40kHz, it is just the 1734-IJ is not reading it properly...

If I change my output to say 30kHz, the PLC reads ~30kHz, which is correct.

It would appear to be read wrong whenever I go beyond 38kHz

Now if I chose to pick "No Filter", I can read 40kHz but the precision is not what I want...

What am I doing wrong? And is there anything I can do to improve the precision?
I have not used this module - so I have no stories to share:rolleyes:


I went through your listed settings - everything looks OK to me. Nothing shouts "this is wrong".


It works up to 38 KHz, so you obviously have things set up mostly correct.


It works up to 38 Khz but not at 40 KHz with a 50 KHz filter - that's just weird.

The results you see at 40 KHz - about 19 KHz - suggest a timing problem. Specifically 1/2 of your maximum measured working 38 KHz.


All of the published timing shows it should work perfectly up to at least 49.5 KHz symmetrical square wave.


If it were me, I'd call tech support. You've tried everything you can think of !!
 

Similar Topics

Hello The plant is running and there is no shutdown nowadays therefore I can add 1734- AENTR and its card while PLC is in Run? I do not wanna...
Replies
1
Views
111
Hi all, This is my first time working with a 1734-IE2C analog module. I am tasked with wiring the flow meter into the analog card and the OEM is...
Replies
2
Views
142
Hello all. I have a remote that uses a 1734-AENTR series C. We had to change it to a new one and, after adjusting the IP and number of slots...
Replies
16
Views
451
Hello, I am kinda new to automation, I had an issue with 1743-EPAC which supply's 13 IO , when we inspected it there was a short circuit...
Replies
2
Views
127
Hello Friends I have took the sample program from AB webpage and modified, but I can only send 127 chars...
Replies
1
Views
156
Back
Top Bottom