We have tried and evaluated:

Siemens Step7
AB Control Logix
Wago
Phoneix Contact AUTOMATIONWORX

They all use call defined "custom" function blocks by sequentially executing them by substituting the variables for each instance after each scan. This makes it impossible to debug a custom block while the processor is running.

We have found only Modicon Concept makes a new Instance of the DFB code each time, so you can drill down and debug the code while is running.

Are there any other PLC development system suppliers who can do this?

Steven Landau
VP
SPEC Process Engineering & Construction

 

Schneider Unity software provides even more diagnostic features and function blocks than the Concept software. You can use the included funtion blocks or build your own. They all log to the alarm logger in the PLC so you can trap faults even while you are not logged into the controller.

 

> Siemens Step7
<clip>
> They all use call defined "custom" function
> blocks by sequentially executing them by
> substituting the variables for each instance
> after each scan. This makes it impossible to
> debug a custom block while the processor is
> running. <

No! For Step7 you have to use the command
<Monitor with Call Path>
from the context-menu of the block.
Try it, works fine.
(The help topics <call path> and <call
environment> explain the conditions to
use this function)

> We have found only Modicon Concept makes
> a new Instance of the DFB code each time,
> so you can drill down and debug the code
> while is running. <

I dont know Modicon, but to me that method seems
poor and wasting memory or speed or both.

Greetz
LargoD

 

Mitsubishi has a European software for its PLCs called GX-IEC-Developer. You can get it in the US but they will only give you limited support. It doesn't bother me much though, I don't need their training or anything. All it is is a high level compiler that compiles to Melsec Instruction list language. It does let you debug each instance of a function block. I've done stuff like have my main window open monitoring, and then you can monitor your function block internals in another window. When you ask to monitor a function block it pulls up a window to have you select which FB instance you wish to monitor. I've only had success doing Instruction list, Structured text (calculations, not control), and Ladder.

I am not thrilled with the Chart implementation, but I've found that everyones SFC implementation is kind of piggy on resources (I haven't looked at Modicon, only AB, Siemens and Mitsubishi). I can't recommend chart for control sequencing at lower levels because of this and other subtle issues. I've been pretty happy with the mitsubishi IEC with ladder though.

Another nice thing about Mitsubishi IEC developer is that you can have real libraries. Yes, Libraries, not manual importing of code from another project, which is what some companies call a library. So if you update some FBs that are used on a few different machines using that library, you just hit "update library" and recompile and your common code changes are implemented.

The normal US product GX-Developer has FBs and stuff but it is really limited compared to GX-IEC. There are things like 16 and 32 character name length limitations and something like 256 step limits on function blocks. GX-IEC Developer doesn't seem to have any of these [seemingly] arbitrary constraints. )

~KEJR

 

Schneider Electric Software Packages:

Concept (Currently at Version 2.6)
UNITY (Currenlty at Version 2.01)

 

Steven,

Try the Bristol Babcock ControlWave PLC. They implement all the IEC 61131-3 Programming languages as DFBs and my understanding is that you can do online edits without rebooting. We will be installing a few of these in an upgrade project, so I don't know all the particulars.

Bob

Robert J. Dusza, Jr.
Project & Technical Support Manager
(V) 1-860-647-3219
(F) 1-860-647-3150
E-mail - [email protected]
Manchester Water & Sewer Dept.
125 Spring St. P.O. Box 191
Manchester, CT 06045-0191

 

As far as I get from your question and I have worked over STEP 7 u can get individual instance for each function for that you have to use FB instead of FC and for more clarity disable the multiple instancing function for any more help.

[email protected]

 

I've used a software package called Think'N'Do. It's a HMI and uses flowcharts (MS Visio) for the program instead of ladder logic. It all runs on the same PC with external IO.

 

G&L also has PLCs which make extensive use of user-defined function blocks. You can monitor/edit these blocks online. The controller also does an excellent job of motion if that is a concern.

Matt

 

Siemens Step 7 are fully compliance with IEC-61131 standard;

PLease call in SIEMENS for full demonstration.

With S7-400 modification online is possible in software as well as hardware modification.

 

In the WAGO IEC61131 software, the internal variables of any function block can be viewed during processing by expanding the function block variable name in the editor. Another way to view internal function block variable is to use the watch and receipt manager located in the resources tab of the main screen. There you can make a custom list of any variable you wish to actively monitor and or control during processing.