S7 Pro online programming

Just commissioning a job at the moment and I wish to do online programming changes. My client has been working for 15 years with Siemens and he tells me that when programming in ladder and doing online changes you have to go offline, change the rung, download the whole FB and then go back online.

I was wondering if this is correct or if you can do online changes without having to muck about like this? Also, is there a simple way of changing an N/O contact to N/C or do you have to insert an N/C and then delete the N/O?

I am hoping Siemens is not so unfriendly that one has to change programs online in this way. I am used to doing what I want and just hitting the / key to change a contact orientation.

By the way gentlemen, thank you to those who assisted me with finding a more economical Modbus RTU solution. It is working fine. My client is wrapped as Siemens Australia had not thought of the Profibus Modbus solution and he had been running away from Modbus at a million miles an hour. He has now ordered a number of modules to read data from chillers, power meters and all manner of devices.

Afraid that is correct for Siemens. Doesn't have the old pre and post change screens like Allan Bradley.

But then again, Siemens is all about programming in small chunks, the modified block is all that gets transferred.

If you are monitoring on-line and start editing it automatically goes off-line in edit mode. Once transferred it usually goes back on-line. If you want the ability to 'test' the change ALA Bradley, you would have to parallel the change with existing and use a spare flag to choose between branches.

Its sometimes good practice to save the block to another block before hand, so if you change you mind after making a large change you can go back.
Depending on the size of memory you have as well, you may start running out of memory if you make a few changes, even multiple changes to the same block. Siemems re-writes the block in another area of memory and the old block area just becomes redundant. BUT don't panic, you can compress the memory to 'fill' all the gaps and recover your full allocation of spare again.

Did't see your overwriting bit. Yes, the INS button as per normal windows, Step 7 automatically starts in insert mode, pressing INS toggles between insert and overwrite modes.

Thank you Peter. What a pain!!!!! Another silly question - right click when online brings up a dialogue "set to 1" and "set to 0". This is quite handy but is it a force? If it is a force does returning the bit to the original state remove the force?

By the way, not into AB but Omron. AB has too many memory areas - Omron is just basically a couple of big sheets of I/O of different kinds and you can really do what you like with it. Software is reasonable also and includes everything right through to NC cards, Device Net Configurator, Profibus Configurator etc etc at a smaller price than S7 basic. Does all the PLCs too - just one set of software.

I have not used Siemens for years and I was hoping they had fixed the software - it is better but not much. I guess I am a bit limited as I do not use STL and ladder is still specified in most specifications here in Ozz. Even had a mate who used FBs. Had to re-write the program without FBs to comply with the spec and then re-commission the job from scratch and pay everybodies expenses for the testing because FB is not ladder - although ladder was used inside the FBs.

Another thing I find interesting is how slow the comms are. Absolutely forget the serial link!!!!! I find that the ethernet link does not appear to run much faster than the Omron serial link running at 115kbaud except when monitoring several PLCs over the serial link and then the Omron serial driver really slows down.

The forcing bit no, all that is doing is allowing you to change the bit (it works with words as well if you wnat to put a value in), if the code wants to change it back, then it will.

You can force things though, create a VAT table and put in the things you want to force, highlight them and select from one of pull down menu's show force table (sorry dont have the code in front of me, otherwise I would be a bit more precise). The things you highlighted would then be shown in a force table. You can then set them as you want. A light on the CPU (400's here) tells you a force exists).

FB's and STL, that was S5, you can use ladder in FC's and FB's now. FC's are basically the old PB's with a bit extra. (EDIT: Thinking of it FC's are more like the old FB's with ladder)

Basically you can program everything in ladder, I liken it to tying your right arm to your left leg behind your back before starting a marathon, you can do it but your hindering yourself.

I prefer to write the main logic in ladder and then the common sub-routines in STL (who am I kidding, I'd write it all in STL).

Last time I used serial was with a Modicon, now virtually everything here is Profibus orientated, I'd look for an alternative supplier if they told me serial only.

The system I'm working on at the moment is all Profibus and Asi, with a few ET200s's (on Profibus of course).

A bit of advice, if your looking at passing data between PLC's and you have profibus, the DP couplers are the easiest and quickest option.

Another thing I find interesting is how slow the comms are. Absolutely forget the serial link!!!!!

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Yes. It has been posted many times that the serial MPI PC adapter should be avoided. As there is much faster USB PC adapter at the same price, there is no reason to use the obsolete serial adapter.

I find that the ethernet link does not appear to run much faster than the Omron serial link running at 115kbaud ....

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Which ethernet link are you using ? And which PLC ?
I find that the onboard ethernet port on the "PN" CPUs is very fast.
The CP modules for the S7-300 are handicapped in that the connection to the CPU must pass the relatively slow serial backplane.

The forcing bit no, all that is doing is allowing you to change the bit (it works with words as well if you wnat to put a value in), if the code wants to change it back, then it will.

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Thanks for that. I have placed an N/C M bit in front of each rung so that I can turn the rung on and off. The bit is not used anywhere else in the program.

You can force things though, create a VAT table and put in the things you want to force, highlight them and select from one of pull down menu's show force table

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Have already been there with no program in the controller to check out the I/O wiring. Quite handy.

As there is much faster USB PC adapter at the same price

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I am using my clients equipment here. He normally just hooks in on the hospital ethernet network. I have now done this through a switch at the PLC but I have to disconnect the hospital network so that they cannot detect my unauthorised laptop.

Which ethernet link are you using ? And which PLC ?

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318/2 with onboard ethernet. It is not bad but slower than I thought it would be. These days I normally use Bluetooth into the Omron serial port (after setting the serial port up) at 115k and it is really quite fast. I can then walk around the plant with laptop in hand. That is a HUGE bonus - no wires for big footed electricians to fall over.
Thanks again you guys.

Also, maybe you are already doing this, but it helps a lot to learn the Siemens hot keys. For instance, "CTRL L" downloads the code, and "CTRL F7" goes online. Once you get used to this, you will be flying on S7. I was so used to using hot keys while using the old S5 PGs (675, 685, etc), that I just kept on doing it with S7 and have even turned off the tool bars. It sure frees up a bunch of real estate on the screen for working.

Also, maybe you are already doing this, but it helps a lot to learn the Siemens hot keys. For instance, "CTRL L" downloads the code, and "CTRL F7" goes online. Once you get used to this, you will be flying on S7.

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I am doing this now thank you. I am really used to using hot keys for everything but am also used to programming my own. I have discovered some with Siemens but not that many. Will investigate further if I get another job with Siemens PLCs and that seems quite likely with my present client.
Like all PLCs and programming software, there are good and bad points. It is a matter of getting used to both and working around the bad.
I did find another absolute annoyance, my client asked me to move some words I had used for timer values. I changed the word numbers in the symbol editor and, as most software appears to be symbol driven these days, expected the word values to change in the timers throughout the program when the symbol table was saved. NO WAY!!! Had to go and change all the word numbers throughout the program manually. There may be a quicker way but I have not found it.
I must also say I am used to a change in the symbol table being reflected immediately in the code without having to save the symbol table first.
Just as a matter of interest, most (all?) manufacturers do not appear to have a feedback service with respect to their software and hardware for users to make suggestions, or not an open one anyway. Bit like Microsucks if you have an OEM version of Windows - no way to report a faulty product. At mrplc.com there are a couple of threads running in the Omron forum re requested improvements, and annoyances, with the Omron software. Apparently big brother is watching. I think this is an absolutely excellent idea and more manufacturers should be watching these websites or put in place an open forum at their own website where users can vent their spleens and/or make suggestions to make all our lives easier instead of having to put up with inferior/faulty/buggy products/software. I guess the problem with a company owned website is that they may do what AB did when someone "had a go"! Better to be here or at mrplc.com I think.

There are two options open to you to change ID.

The first is the re-wire option, where you highlight the blocks you want to change and enter what you want to change from and to, if the changes are too many or overlap then it can be difficult.

The other way (an simpler) is to convert all the program (or just the ones with the changes if they are known) to source code, ensuring its been done with symbolic names and not absolute addresses. Then change the symbols in the symbol file and then re-compile all the source code.

The link is to the Siemens programming manual, which is very informative and also lists all hot-key designations.

http://support.automation.siemens.com/WW/llisapi.dll?func=cslib.csinfo&lang=en&siteid=cseus&aktprim=0&extranet=standard&objid=10805382&DataKey=10805382&treeLang=en


select Programming with STEP 7 V5.4 .

Quote:
Which ethernet link are you using ? And which PLC ?

318/2 with onboard ethernet.

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I dont think that there is a 318 with onboard ethernet. Presently the only models with onboard ethernet are the 315-2PN/DP, the 317-2PN/DP and the 319-3PN/DP.
Either the 318 you are working with has a CP343-1 in the rack, or there is a MPI/Ethernet adapter. Several 3rd party vendors have these MPI/Ethernet adapters. If there is one of these attached to one of the two MPI or DP ports on the 318, then it may look like it is directly attached to ethernet.
If the port is the relatively slow MPI port (187.5k) then it explains the slow speed.

BobB said:

I did find another absolute annoyance, my client asked me to move some words I had used for timer values. I changed the word numbers in the symbol editor and, as most software appears to be symbol driven these days, expected the word values to change in the timers throughout the program when the symbol table was saved.

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This would have worked if you had chosen "Symbolic Priority" first (right click on Blocks and select Object Properties). If that had been selected, you could have changed the absolute value of the symbol and the code would have changed automatically.

Siemens' strong point is in its symbolic programming, so I have pretty much used Symbolic Priority for years, but I know when new projects are created, it defaults to Absolute Priority. It's easy to overlook this.