OB16IEF not generating PWM

Hey all,

I'm trying to use a OB16IEF to generate a 24V PWM signal. According to the manual all i have to do is set...

Local:#:C.Pt[#].PWMEnable = 1
Local:#:C.Pt[#].PWMCycleTime = My wanted cycle time
Local:#:C.Pt[#].PWMOnTime = My wanted on time

Then when i set Local:#:O.Pt[#].Data = 1 the output should be generating a PWM.

For testing purposes i have set the cycle time to 10 seconds and on time to 5 so i can use a multi meter to test if the signal is changing.

When i set Local:#:O.Pt[#].Data = 1 the output created the high signal but it doesn't turn back off (generate PWM). I have read the knowledge base article on the firmware 1.011 anomaly causing outputs to stay on. I've flashed to 1.012 so that shouldn't be the issue.

Does anyone have some experience with this card that may lead me in the right direction?

Thanks to anyone who can help

This is a 5069 module, correct ?

Are 10 seconds / 5 seconds even valid PWM values ? Obviously ordinary PWM signals are several orders of magnitude faster.

This is a 1756-OB16IEF module. According to the data sheet, PWM on time can range from 0.0002 to 3600.0 seconds so a longer PWM shouldn't be an issue.

I did purchase the module to control a stepper motor though at 800 steps/rotation so I will be using it at a much higher speed than this. I just want to verify that it is working for now.

Thanks !

Are you using the Config tags or the structured tab for the module configuration ?

There's a Knowledgebase article that gives some more info on time v. percent mode, and limiting to a specific number of pulses.

https://rockwellautomation.custhelp.com/app/answers/detail/a_id/638809

I am using the configuration tags for the PWM Enable, but the Cycle/On Time are output tags that I also set continuously in the program. Looking online at the manual the config tags are described as "Structure of data sent from the controller to the I/O module upon powerup"

My 1756-L63 does have a bad battery and has to download the program every time I cycle the power. That would mean that I'm sending 0 for all configuration every time i download. I could try setting the configuration from the module properties, or maybe I'll replace the battery and see if that fixes anything.

What do you have for wiring?
Check Local I for faults
Set master clock?
Try different output

A while back, one had to send a MSG to the module when the config file was changed.
Can't find a document, but I think it was something like:
MSG Type: module reconfigure, or maybe CIP Generic, Service type: reconfigure

Can someone find the how-to for module reconfigure MSG instruction? I think they've removed it from the current manual. The title of Appendix C of 1755-um058 sort of hints at it, but there's nothing in the body.

AustralIan said:

A while back, one had to send a MSG to the module when the config file was changed.
Can't find a document, but I think it was something like:
MSG Type: module reconfigure, or maybe CIP Generic, Service type: reconfigure

Can someone find the how-to for module reconfigure MSG instruction? I think they've removed it from the current manual. The title of Appendix C of 1755-um058 sort of hints at it, but there's nothing in the body.

Click to expand...

Module Type: Module Reconfigure.

But that is for the purpose of updating module configuration without interrupting the connection