What is your favorite PLC language?

[marmot 0]

As the title says,what is your favorite PLC Lanuage,AND the more important question is : why?

I'm not judging those lanuages,I just want to know something  you guys think about this.

Lanuage List:

• ST
• LD
• SFC
• FB
• IL

Thanks.

Edited 14 Mar 2016 by marmot

[Nightfly 12]

ST.

It's not very elegant for bit logic but it has one major advantage. It can be copied and pasted between most PLC's provided you make your code as generic as possible (try to avoid using functions only built into a particular PLC). Our equipment is complex and would run to hundreds of thousands of rungs if coded in ladder (and would take several months to re-code between different PLC vendors). Keeping a single code base in ST means we can add features to the system knowing all new orders on whatever PLC the customer chooses will get all the new features and will be as far as possible tested. 

Same with the HMI. We find companies tend to be insistent on the PLC, but far more flexible with the HMI. We use the Beijer IX series HMI's as standard (simply because our recipes run to over 30k word registers and include images). If the customer insists it has to be a particular brand we just run the IX software as a app on the customer preferred brand PPC. Apart from re-tagging the OPC variables to the new PLC there is no need to touch the HMI code.  

Often the case against using ST is that it is not "maintenance man" friendly. This is a point I do have some sympathy for (however on a couple of jobs the original URS has specified only ladder - but the customer soon changed their mind once we update our quote to reflect the re-coding required).

 

 

 

[marmot 0]

Are there some software which support converting between LD and ST?I think this wil make you happy.

 

You mentioned LD,why lots of people like LD?

Thanks.

[kaiser_will 65]

I am most comfortable with Rockwell/A-B Ladder, but I found my favorite to be flowcharting in Steeplechase VLC (PC-based control).  We had a project with a very tight servo loop update time spec (1-2ms) and the flagship ControlLogix CPU (L6) could not pass the testing requirements at the time.  The PC-based Steeplechase VLC card and programming software did the trick with wonders, except one has to turn off all of the PLC programming experience to switch to flowcharted programming.

[Crossbow 295]

I prefer to write most of my program in LD, and include bits of ST as required.

LD is best for discrete control.  Simple bit logic is easy, and most customers who have programmed PLCs in the past (and electricians who can read a power flow schematic) are able to easily understand it.  LD was created for electricians.

ST for any kind of comparison, looping process, or math.  It's just easier to write than having to create a bunch of functions and function blocks in ladder.

Also have used SFC (great for sequencing) and FBD in programs in the past.

[Joe E. 259]

I'm an end user running production, not an OEM.  I stick with LD as much as I possibly can for one very simple reason: I don't like 3AM phone calls. 

Actually, there's another reason: I don't like paying thousands of dollars extra PER SEAT to get access to the other languages.

If the extra languages were reasonably priced AND if we had off-shift support who understood them (or could learn them easily), I would probably use other languages for certain things.  We have a few machines that came from the OEMs with FBD and most of our Siemens PLCs have at least some STL (which is a VERY effective way to ensure 3AM phone calls).

Our PLC platforms are Allen-Bradley (SLC100/150, PLC2, PLC5, SLC5/x, Logix5000 v11-24) and Siemens (S7-300).  It's an old plant....

[AngryRobot 8]

I prefer Ladder.  Honestly I've never done any ST except for a few brief examples in training classes.  I work for an OEM and some of our customers don't even like function blocks in their programs.

I would like to get the chance to do some real ST programming; but really ladder makes the most logical sense to me.  I tried learning C once and I just couldn't really get into it.

[Inntele 60]

I prefer to use a mix of LD/FBD and IL in the project. IL allow to get a shortest compiled code and a minimum of temporary variables, allow to bypass bugs in the programming software, made by its developer. Often I use this language to write communication drivers, various user libraries (RTC, analog processing, archives) and sometimes FBs, related to internal algorithms for sensors/actuators. While for the global control sequence I use only LD/FBD, because it provide the best visual readability. This property is extremely important property for the good automation project, that allow easy to make changes in the project after years. Moreover, all we are mortal, however the project must not only continue to work properly in the PLC, but also to give for an engineer, who will replace you, a possibility to understand how the program works, and, if it's necessary, to make the appropriate changes without enormous efforts.

I consider, ST is a bad language for PLC Programming, because its compiler give a long, non-optimal code and the project will not have a clarity.