louisgermain6 Posted January 20, 2020 Report Share Posted January 20, 2020 Hey guys, I'm currently on a project using a US7-B5-TR22, one idea is to use the PWM output to command the frequency of an inverter. I know outputs needs to be enabled as a PWM output so I made a button to activate them when I use the inverter. The thing is that I don't have the inverter here to run some tests, and I wanted to see if the signals were as I wanted them to be. I measured them with an oscilloscope to verify and I can see that the output has the correct frequency, but the signals are about 2mV and of course really noisy. I'm wandering if I'm missing something here or if it's just normal ? In the documentation it doesn't say anything about it. Any idea ? Thanks you guys. Louis Quote Link to comment Share on other sites More sharing options...
DanT Posted January 20, 2020 Report Share Posted January 20, 2020 Hi; What kind of load did you use: The NPN output is Open Collector, No Pull Up. Add a 2k2 or greater resistor from output to V+ and check on o'scope. and scope ground on CM4 DanT Quote Link to comment Share on other sites More sharing options...
louisgermain6 Posted January 20, 2020 Author Report Share Posted January 20, 2020 @DanT Hey, I've been checking as you said connecting a 3.3k resistor pull up to my V+ and the scope ground to CM4. Results are that the signal is powered up but I have the 50Hz frequency... I didn't put any load before the scope and I don't know yet the type of inverter that I will command. Thanks for your quick answer. Louis Quote Link to comment Share on other sites More sharing options...
DanT Posted January 20, 2020 Report Share Posted January 20, 2020 Hi; Are you able to vary the Pulse Width and observe it on the o'scope? ( remember 100 = 10.0 % width 1 decimal place ) DanT Quote Link to comment Share on other sites More sharing options...
louisgermain6 Posted January 21, 2020 Author Report Share Posted January 21, 2020 @DanT Yes, I'm able to do it and I can see the change. It seems to be more an electrical problem as when I connect the 24VDC : the 50Hz is add to my signal.. Quote Link to comment Share on other sites More sharing options...
louisgermain6 Posted January 21, 2020 Author Report Share Posted January 21, 2020 @DanT I found that the CM4 is not internally connected to the same supply network that the PLC, it's separated from the alimentation so I think the 50Hz emission comes from my scope which doesn't have a earth reference. I was thinking about pulling up the HSO-0 with the 10V of the inverter and connect the CM4 to his 0V so I have the same reference but documentation advise me to not do it if I don't misunderstand... Quote Link to comment Share on other sites More sharing options...
DanT Posted January 21, 2020 Report Share Posted January 21, 2020 Hi Louis; Contact Unitronics Support directly -- or call them - get their number from your local distributor. Their Asian and European support is from Israel North American support is out of Boston support@unitronicsplc.com DanT 1 Quote Link to comment Share on other sites More sharing options...
louisgermain6 Posted January 21, 2020 Author Report Share Posted January 21, 2020 @DanT will do, thanks for your help. Louis Quote Link to comment Share on other sites More sharing options...
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