Structured Text on a PLC-5

antjon1

Member
Join Date
Feb 2006
Location
Tennessee
Posts
29
Does anybody know where I can find a good guide online that has information about structured text programming with the PLC-5? I am familiar with BASIC, however I can't figure out how I need to format my commands in the structured text file to make it work. I am constantly getting verification errors. Thanks!
 
I've never used ST on a PLC5, but the online help in RSLogix 5 V7.0 looks pretty informative. I couldn't find a manual on-line that seems to address ST on a PLC5.
 
be careful what you ask for ...

Greetings antjon1,

if you followed the "default" installation pattern for RSLogix5, then you probably have a good example already on your hard drive ... see if this helps ...

stxsample.JPG


if you don't have this file, post again ...

and welcome to the forum ...
 
I just had a thought ...

... structured text programming with the PLC-5? I am familiar with BASIC




I’m just guessing here ... if I’m all wet then feel free to just disregard this post ... but something is telling me that this is your situation:



you’re trying to use your existing familiarity with “structured” type programming languages (BASIC, etc.) to “cross-over” into PLC programming without having to learn and deal with “ladder logic” programming ... maybe you’re thinking “why learn all this new way of doing things when the PLC will let me keep on programming pretty much the same way as I’ve been doing?” ...



I’ve heard that same story several times before ...



if that’s your situation, then we probably need to talk ... simple truth: you cannot work with PLCs for very long (usually MINUTES, not days) without coming to grips with ladder logic programming ...



now this thread is probably going to turn into a debate on which is better ... structured text or ladder logic or even sequential function charts ... and mention will be made that one method is better than the other for certain types of applications ... I’m not trying to start that debate ... all I’m saying is that if you think that you’re going to work on PLCs without having to deal with ladder logic, then we need to talk ...



but maybe you’re already ok with ladder logic ... you didn’t say - so how could I know? ... if you’ve already got a handle on it, then just ignore this post and party on ...
 
I am actually in school for PLCs, and have already covered ladder logic pretty well. I've played around with BASIC some when I was younger (mainly on my graphing calculator in High School, but other places as well), and I wanted to get familiar with how the PLC 5 and RSLogix 5 wants everything to be formatted. So far, I have been able to write a small program for it that worked pretty well, however, the help file didn't really seem as informative. It gives the list of instructions that it supports, but very little on how to use them. The biggest hting that was confusing me is how "real-world" outputs and also the PLC addressing system for I/O fit into things. I'm used to printing a string of text on a screen, or a number, or putting in instructions to calculate things. I'm not experienced with having real devices other than a PC monitor to output to.

I haven't checked yet if my version of RSLogix has the ST example file, but I will look into it when I get some time back on the PLC.

Thanks for the warm welcome, and also the very timely and informative response. I can definitely tell that you guys enjoy your field (not saying I don't, bc I love this stuff), and that you are very willing to help!
 
great! ... I hereby retract anything that might have possibly sounded discouraging about learning structured text ...

and if you'll get together a detailed list of your system's inputs and outputs, we can probably help you nail down those ideas ...

come back often ... you'll fit in very well around here ...
 
The trainer's that we use are manufactured by Amatrol. From what experience I have on their equipment (we have more than just plsc, theres a motor control/electrical systems trainer, pneumatics/hydraulics trainer, and a mechanical drive systems trainer) it is top of the line. the setup is fairly simple: there are 2 24VDC input cards and 2 24VDC output cards. Slots 0 and 2 (1 and 3 for SLC500) are inputs, which each come from one of 2 simulator panels, and there are 2 outputs on slots 1 and 3 (slots 2 and 4 for SLC500), one for each panel. Their panels include an operator station, with 3 NO pushbuttons and 1 NC pushbutton, along with 1 2 position SS and 1 3 position (on off on) SS. There is also a reversing motor panel, with a small DC motor, 2 relays, one for each direction, and 2 limit switches. There is also an I/O simulator station with 16 switches and 16 indicator lights. Theres a pneumatic panel, with 2 cylanders, one with a 2 position sol valve, and one with a 3 position sol valve. Theres a BCD station with a thumbwheel and an 8 segment LED display. Theres also an analog simulator with a pot to vary input voltage,a nd a voltmeter display, to display actual input voltage, or display output voltage.

I learned almost all of my ladder on a SLC 500. Its the main PLC that is used for teaching. We are going over the PLC 5 so that we can learn differences. Later on, we will be mounting a ControlLogix on there, as well as a Siemens. Not sure on the Siemens model no. though, bc it is brand new.

One of the most interesting things aobut the Amatrol trainers is the fault system. The PC is connected to a special terminal on the trainer, which goes to several different places. It can fault out switches, relays, fuses, the MCR relay, and even fault I/O cards. It has helped me quite a bit on the job, bc it makes it easier to troubleshoot. You can learn what specific symptoms are for certain problems and have a better understanding of them in the field. I am employed as a maintenance technician at one of our local plants, and I got that job bc of hte training I've gotten here.

OK, anyway, thats the whole setup and background info. I'm not looking to develop a specific application for it right now, I jsut want to see what I can do with ST, and how flexible it is. I like using ladder bc its easier for me to see just exactly what the PLC is thinking, but I wanted to explore what there is to offer.
 

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