stl in Qxx

[skiv71 0]

Hi, I've used STL programming extensively over the years within my normal ladder logic programs (you might call that embedded). I'm just doing a Q02 project at the moment and I thought the STL would come in handy but i dont think it does it. Am i right? If it cant thats a right bummer! I know SFC is nearly the same thing but i've never written SFC style. If it requires SFC, can a SFC program co-exist with the normal ladder logic? Thanks Neil

[Goody 5]

No, true STep Ladder does not exist in either the A or Q series (and you are right, its a bummer) But 'S' relays can be used. (to maybe indicate the active Step or Stage) But the whole program is scanned - not just the active step. I have never used SFC so I cant help you there. If this is your 1st time with a Q then you really do need the full instruction list as there are many more - plus lots of usefull FX instructions do not exist. (ZRST for 1)

[skiv71 0]

Oh i was starting to suspect this. I've done plenty on A/Q ranges just never had to use STL, although i've used it loads in the FX series. Thanks for your help in confirming this :o) Neil

[panic mode 246]

it is true that some of the FX instructions didn't find their way into larger processors. maybe i don't miss them because i use FX only rarely. i prefer FMOV over ZRST, because ZRST can do only 50% of job (reset) but that's me. on the other hand FMOV is also available in all cpus.

[mikeb 1]

The Q series has a command BKRST which allows you to reset a block of bits. eg BKRST M0 K20 would reset all 20 bits from M0. Mike B

[Colin Carpenter 10]

I'm the same ..... used STL instructions extensively in FX PLCs for processes that stepped through in sequence, to the extent that when I had to write a similar process using an A Series, I looked really hard for an alternative, and there is a good simple one. Check out the Commands MC (Master Control) and MCR (Master Control Reset) An MC command when enabled, "energises" the rungs between it and the next MCR command in the programme, which, if you think about it, is much the same as an STL command. So, energise the MC command at the start of your "virtual Stepladder" and energise the MCR at the end of it when it's done, having energised the next MC command to create the next Stepladder etc. etc. Works fine ..... believe you can also nest these things as well, but haven't tried that.

[skiv71 0]

Hi, Yeah i've used mc etc and extensively with nested loops, but i wouldnt use em here unless there was several runs in each stl equivalent. I ended up coding my own stl equivalent, with sets and resets etc. Works fine :o) Thanks for your input anyways. Neil

[Colin Carpenter 10]

On another topic, I re-read an old thread where you had managed to get transparent comms between an E300 HMI and a PLC using a freeware Ethernet / Serial driver. I've got it all set up on the bench but can't get comms to the PLC. Any chance of telling me the settings you used in the freeware driver, please? Thanks

[Colin Carpenter 10]

I think I've pretty much sorted this out now. It seems that the freeware driver only opens the virtual port at a speed of 9600 baud, while the Q2AS needs 19200 to communicate. I downloaded a trial version of one of the commercial serial / IP drivers and it all works fine on that one. The freeware one would probably be OK on the FX family which I think use 9600 baud for comms, but unless I can work out how to change the Baud Rate I think I'm stuck on this one.

[skiv71 0]

Hi, the one I use quite happily does all baud rates. I'll have a look at work tomorrow to confirm my setup. I've got a dialup system to a remote dite with a remote router in place with 6 HMI's connected with a variety of PLC's, Q00J, A1SJH and A3N. Regards Neil

[Colin Carpenter 10]

Thanks, Neil I've tried for another few hours and can't get it to work (the freeware one from HW-Group). As soon as I uninstall it and load the trial one from Tactical Software it works flawlessly. Looks like I might have to shell out for it