GE Fanuc 90/30 Alw_on

Is there a way to stop a 90/30 PLC deleting an Alw_on (%S7) contact placed at the beginning of a rung when it compiles a new program?

It's not a major problem, I can get round it several ways. It's just a bit annoying.

TIA

One way would be to use Logicmaster software.

Another way would be to not upload the program from the PLC to your PC. Proficy ME software will maintain the usage of the ALW_ON variable, but when you upload from the PLC to the PC, it does not interpret horizontal shunts as an ALW_ON contact.

Thanks Steve

Only trouble with not uploading is that you don't get "logic equal" then you can't monitor.

If I use a normally closed of Alw_off (%S8) do you know if that will be left alone?

Only trouble with not uploading is that you don't get "logic equal" then you can't monitor.

Click to expand...

If the computer that you use to monitor has the program folder that matches the PLC program, you don't need to upload to achieve 'Logic Equal' status.

If I use a normally closed of Alw_off (%S8) do you know if that will be left alone?

Click to expand...

A long time ago, when I was in college, I asked a question in class one day. The professor responded, "I think that is an excellent question that deserves further research. Please report your findings to the class by next week." In that same spirit, I think you're right and that it would be rendered correctly. Please report if your experimentation confirms it.

The latter question was one I was going to find out myself next time I'm connected - I'll post my findings.

I'm doing this project via. PC Anywhere over a 56k modem so was just trying to save a bit of time and effort if anyone new the answer for definite.

Thanks

A N.C. contact of %S8 remains in the ladder even after uploading.

BTW this PLC is connected on site to a PC running Versapro so I don't know if the same result would apply if Proficy ME were used.