1769-HSC, need retentive count after power-up

[slcman 9]

Hi all, I need to keep my count after power-up. I tried tech note #63317 ( http://rockwellautomation.custhelp.com/app/answers/detail/a_id/63317/related/1 ), not working in my plc. I tried again but this time I put enable bit to zero as tech note 21205 asking for ( http://rockwellautomation.custhelp.com/app/answers/detail/a_id/21205/kw/21205 ), again, is not working. PLC is compactlogix 1769-L32E firmware 19, ( PLC, HSC, HSC, Power supply, Input, Output, end cap) 1769-HSC take more time than plc for boot. So OK and run LED on plc turn solid green before 1769-HSC OK LED is solid green. This means first scan of plc want to set current count while HSC is not ready. AB Tech note use first scan, I call support and they don't have any issue with this logic. Maybe they switch plc mode from program to run, by doing this they got first scan with HSC OK LED solid green. Another option is to use GSV insctruction to get HSC module state. I found logic for contrologix ( http://rockwellautomation.custhelp.com/app/answers/detail/a_id/57569/related/1 ) but nothing for compactlogix. Once GSV instruction tell me module is OK, I will write current count value. I left 2 screen shot, before and after power up. My current is alway 0 after power-up, really need your help now. Can someone can test tech note 63317 with a real power-up? thanks

[IO_Rack 181]

I had the same issue with the same hardware as you. I was unaware of the tech notes. What I did as a workaround was take samples from the HSC, subtract the difference then add them to a Logix tag.

[rdrast 3]

Do this. It is worlds simpler in the long run, and gives you much more control over your counter then you ever thought possible. If you are using it in a Compactlogix system, and have FBD, feed the raw counter value through a PMUL instruction, with a word size set to something normal, like 12 or 16. Every scan that you care about the value, add it into a separate register to act as the real count value.

[slcman 9]

god ! So simple, and I do similiar logic when I program absolute encoder. I was stuck with AB tech note but you idea is better! Rockwell didn't send me any feedback on this issue. I have tech support contract, I call, I left email...nothing. Is look like they don't want to tell me tech note didn't work. I'm sure a lot of people got this issue. thanks for your reply