Hi all,

Post first AB project loose ends

Micro 1100, RS500, PV C600 ethernet to PLC (1.5metres)

Not that long ago I was playing around with the new C600. This was my first HMI project, also, my first AB ladder program. (Got a few Mitsi projects under my belt, now I don't want to go back to GX developer, i'm a converted man!) As a 4 year industrial sparky turned (cheers boss ) junior programmer I learnt something, and I was hoping for some re iteration of what I think I found.
In my project I had heaps of alarms and helpful messages for the operators. As I triggered the alarm bits, the alarm would sound as this was sealed in, yet no message on my screen. Hmm, thats weird. Alot of my alarm bits were only on for 1 scan. So i concluded that the screen wasn't seeing the bits trigger. So I changed all the alarm bit outputs to latched. Why was this so? Have I found out about update / refresh times over ethernet? Are there some rules of thumbs to apply on my next project? I.e bits should be on for a minimum of say... 500ms? Anything else of major importance I should also read up on???

Side question, whats the easiest way to reset a sequential range of bits that are latched (OTL) on? Mitsi has a zone reset (ZRST) I had a brief hunt around in the manual, nothing obvious stuck out at me, and I dont have a PLC currently to play with so I cant try doing a MOV #0 to those bit addresses.

Many thanks for any replies.
Nathan

If it's only 16 bits (1 word), then a MOV #0 is fine. If it's more than one word, check out the FLL instruction.

You should latch your faults for the best chance at catching them on the panelview - sometimes the communications hiccup and you still might miss it - even after 500msec. The panel will definitely miss a bit that is only on for 1 scan.

I had ethernet comms between a panel and a PLC fail on me once: one time I was jogging a servo on a large gantry and the panelview didn't get the 'he let the button go' event to the PLC, so the servo kept on joggin' until I had to hit the e-stop.

Thanks guys for the responses. File fill is exactly the instruction i need. Good to know it will work next time I write a program. Not having a PLC to test on is a drag. Heading back out to the job this friday so I will tidy up the resets on the alarms.

CLR for single 16-bit words and FLL for multiple sequential words work well.

Minimum bit on time to be picked up by HMI depends on how often the HMI is checking the PLC for changes. It would be really rare for the communications to happen at the right moment to catch a bit that is on for one scan. It generally works well to latch alarm bits on and have them cleared only on a command from HMI, such as a clear faults button.