Q2AS Memory Card

[Colin Carpenter 10]

For what it's worth, I spent a very long time yesterday trying to fault find on a Q2AS CPU that showed every sign of being perfectly OK until the programme started running in anger. Bugs were just coming out of the woodwork as and when they felt like it, counters were counting even though the ladder rungs weren't true, timers weren't resetting and were staying "done". Every verification test I did was fine, there were no system errors and no user errors. After about six hours of despair and wondering if I was ever going to get home, I remembered that I'd seen one of those "PCMCIA" type Mitsubishi Ram Cards inserted in the CPU, so removed it and, lo and behold, suddenly we had a normal "rock solid" Mitsubishi CPU. After talking to tech support, it turns out that one of these ram cards can, if switches are set in a certain manner, causing the processor to apparently try and run your programme in the normal ram area AS WELL AS whatever programme is stored on the ram card ....... and you won't even know it, until things start turning pear shaped, that is. Moral is .... if you don't fully understand it, take it out. PS . If you've got a MAC screen with an Ethernet card in it, then the latest freeware Virtual Serial Port ( creates serial transparent comms through the ethernet connection) from HW Group works perfectly. Thanks, lads. Edited 3 Oct 2006 by Colin Carpenter

[Goody 5]

Interesting. I like to log these things to memory. One day the same thing might be happening to me and a little light might come on...... I love mitsubishi plc's but I have had some weird and wonderful error messages in the past. One that I cant quite remember the wording, told me that transfering the program could result in data errors and losses. Only ever on that one plc (an FX1n) there was nothing unusual about the program but each time I made small changes - I got the message. The machine is and has run happily for 4/5 years?????

[Big Country 3]

Here I got one for you, I could not get online with an A series PLC well let me rephrase that I could only partially monitor some of the program. Well after speaking to Mitsubishi support I was more confused than ever. So I installed a larger processor and was able to monitor the entire program. But none of the error messages that were displayed mentioned anything about insufficent amount memory.

[Colin Carpenter 10]

Thinking about it ..... does anyone know what these SRAM plug in modules are used for in the QNA series? It's always a problem on these larger PLCs to find a time to drop a new programme in without turning off the items that are running, and as more items get added to the PLC, it becomes even harder to find that 1 minute or so when I can shut everything down. It occurred to me that if the SRAM card can apparently hold and run a programme, then it would be really good if I could let it run the old programme while I'm downloading the new programme into normal ram, then seamlessly switch to normal ram when it's done. Failing that, does anyone know a way of downloading a programme to the CPU without the PLC turning off all the outputs? I can handle a PLC that holds it's output state for a minute or so, but I don't want one that shuts down all the outputs as the programme is downloading. Intereresting ....

[waynes 8]

Colin, You can download a program section (excluding the parameters/ special module parameters) to the System Q CPU without stopping it. This of course requires enough free space in the CPU. Simply select 'Online' -> 'Write to PLC' as per normal and select the programs only (do not select anything under the parameters section). Voila!

[Colin Carpenter 10]

Hi Mate, I'll try that tomorrow and see what happens. There's also a section in the IEC DEveloper manual that seems to indicate that there is an Online Programme Exchange function with the QnAS CPUs, as compared to the more normal "one rung" Online Programme Change function. Tech support at the distributors are unaware of this , so I'll see what I can find. Cheers.

[Colin Carpenter 10]

Cracked it!!! Not sure about the Q series with GX Developer, but I now know how to do it with a QNA CPU with IEC developer. To summarise the problem, I've got a Q2AS-S1 PLC which will be running a large(ish) production plant consisting of pasteurisers, homogenisers etc., which rarely sleeps, so access to the PLC is limited. Currently this plant runs in purely manual mode with no PLC control, as it was installed 20 years ago. We have constructed a control cabinet complete with MCC, so 30 or so motors, umpteen valves and umpteen instruments will be coming under PLC control in the next few months, and automation will be applied and modified on a "step by step " basis ..... as we learn more about the plant, so the code will be continuously modified for the best running options. Problem is that as these motors etc come under PLC control, the times when I can stop the programme running and download new code will become very limited and will always be very unsocial. As standard, IEC developer will do online changes, but these are restricted to single rung changes, and you have to select the "online change mode" before altering the rung, then "test", and the rung changes will incorporate themselves into the PLC code in the PLC ram. Fine for one off simple changes, but not much use if you want to write a few hundred lines of extra code, and incorporate that into the PLC ***without the PLC going out of RUN mode**, consequently turning off all outputs. So, you've got IEC Developer, you've got a QnA PLC,you've written 496 lines of extra code and you want to download this without stopping the PLC (or else come in at 1am on Sunday morning when you can have the plant), how do you do it? Answers on a postcard to ................... PS. I will explain how to do it ....... but I'd just like to know how common the knowledge is. UK Tech support said that it couldn't be done, and are amazed that it can - and it's so simple within IEC Developer, just hidden away a bit. PPS. If it's really common knowledge, then it just goes to show how much I've been missing all these years

[waynes 8]

When it comes to tech support, I don't think that they have enough exposure to the real world. (As far as my experience with tech support goes) I think that these guys need to be working in the field with us to say that they can actually do the job. Now, I am not suggesting that these guys be programmers like us, but they should at least know their product thoroughly. I have also asked questions from time to time with no answer. This frustrates me. I think that these guys are experts on their own products only to find out that they know even less... The flip side of the coin is that these guys can help the beginner a lot, but the intermediate/ advanced guys a bit only. I like the easy answer: How is that? Edited 7 Oct 2006 by waynes

[Crossbow 295]

I've found tech support from MEAU (Mitsubishi US) to be pretty good. Some of the guys they have were in the field for over 15 years, and they have some really good talent. But in general more companies these days simply hire people, give them a database of problems and solutions, and say good luck. It's a shame we have to deal with high school dropouts or foreign countries whose English is not good when we call any computer support line. At least most PLC support lines haven't degenerated to this level.

[Colin Carpenter 10]

No, no, don't get me wrong, these guys work for the distributors and are really very good and very helpful .... in fact, they tell me that MItsubishi UK don't actually do a technical help desk anymore, which is a bit of a surprise. What surprised me was that such a useful function ( the ability to download lots of new code without stopping the PLC) is so "hidden away" in the manuals and so "not obvious" in the software, that nobody seems to know about. If I was Mitsubishi, I'd be shouting this information from the rooftops because I'm not even sure that the Allen Bradleys have the ability to do this. To do it, all you have to do in IEC is open the project, then EXTRAS/OPTIONS/PROJECT OPTIONS/ONLINE CHANGE and tick the box that says "Allow online change for inconsistent projects". Default is 500 steps of extra code and 6.0 ms of maximum allowed scan time delay. You can change it to 1000 lines, but you have to do a full download to the PLC afterwards, so that it can reserve sapce for the new programme. PLCs must be later than March 1999. You cannot believe how much easier my life becomes because of this one little check box.