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heron8888

run mode

19 posts in this topic

are there any advantages, having the keyswitch on a processor such as the 5/03, in run mode as against leaving it in rem position?

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Yes it stops the maintenance guys accidently switching to PROG mode while online then wondering why all the plants stopped = Plant stood for a couple of hours until you arrive to sort it.

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The disadvantage is that you have to go to the machine to switch the keyswitch when you want to make a change

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never needed it in run position, that's wrong mode... maybe is important process and you don't want people to accidenataly change program when working through network for example...

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I bet it depends on who you are. Maintenance guy: " Yeah that stupid controls engineer keeps hacking into the PLC and making changes over the internet or from his desk, I wish he would leave that PLC alone!!!!! I am going to put the PLC into RUN mode so he can't make any changes" Controls Engineer guy: " I am going to KILL that maintenance guy, every time I want to make a change, I have to walk 23 FEET, defeat the main disconnect with my PDA stylus, open the cabinet, rotate the key, close the cabinet, stop and get a cup of coffee, then walk 23 FEET back to my desk to make some changes...I am going to leave it in REM mode, and throw away the key....."

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In the interest of fairness consider the following: Maintenance Guy " They sent me to AB PLC school and even issued Laptops to all us electricians and now the Controls Engineers keep leaving the PLC's in Run mode. They claim they write great code and we should stop corrupting it. Like a sensor never fails and needs to be forced. We could play an extra hand of cards each night if they would just leave them in rem. As it is we have to ride our scooter to the cabinet, defeat the disconnect, change the key to rem and drive back to the shop. Controls Engineer " I wish the maintenance guys would just leave these PLC's in Run. I write the code and spend hours debugging it. it passed all the sign off tests and even hit a record last week, but just because their friend the operator wants something changed they place it in rem and mess stuff up. I really hate the 3 am phone calls.

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Well might as well give my true opinion. The TW philosophy The processor switch is in REM mode. Why? Because TW put it there and said not to mess with it If we changed X there is a chance Y would be faster. Should we do it? No, because if you run it by TW and there are no problems including safety issues, the change will be made and you will still get the credit for it. Make it yourself and it turns out bad; run the risk of getting written up or worse. Sure would be easier to bypass this switch and deal with fixing it later. What's the problem? TW going to put a boot up your ....

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Hopefully we are answering your question. I think you can see, there is no right or wrong answer in this case.

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Must be nice to work for a small enough concern where you are the one and only person authorized to make program changes. Unfortunately our 8 production lines and over 100 PLC's require a team of programmers. So we have procedures for tracking changes and reviewing proposed changes. I agree with Chako and expand the thought though, it depends on who you are and who you work for.

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Well I could have expanded on it some more but I'm extremely tired. Pretty much small changes and flaws have to be patched and that is understandable. Major changes need to be looked into a bit further. No one person should make them because it can affect so many people And there are no excuses for laziness That better?

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I put them all in REM and remove the key. Many of our smaller PLC's are in NEMA 7 enclosures, to acces them requires a process shut down, and a permit, plus there are a lot of bolts to remove. To avoid accessing the wrong plc on the network by mistake, they are all password protected. The passwords are accessible to everyone that might need them, via a spread sheet on the file server. This functions as a check off list, if you want to access plc 51A, then you look up the password for 51A, if for some reason you try to go online with 51B, it won't let you go on line with the password for 51A, and hopefully you will realize you're trying to connect to the wrong plc, so far this has worked well.

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Now that is a valid reason for a password. Thanks for the example

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and while we're on the subject of the keyswitch, here's a little trick that sometimes comes in handy ... ever wish that you had a temporary off/on "simulator" switch to use for debugging a system? ... well, on most systems you do ... it's the keyswitch on the front of the processor ... now of course you have to be CAREFUL not to turn the key too far ... but if you use the correct address (as shown below) you can flip between the "RUN" position and the "REM" position and make magic happen ...

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Sounds Like a good system. better than being in Seattle and going on the WAN to fix a timing error with a machine in Baltimore, only to realize you have connected to and placed in remote program mode the entire Atlanta Warehouse facility. And yes this actually happened to my partner in crime on our Seattle job a couple of years ago. The good news it they were only warehouses moving boxes, not a serious chemical process like Rons'

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not bad but by far most systems i've seen are not protected in any way. and when passwords are used, they are usually impossible to guess, something like 1234 or 123 or 321 OR 258!

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For some reason our company has a written process for passwords on any machine. Each piece of equipment is issued a 4 digit # when it comes into the plant. Any PLC or HMI password must be the same as the machine #. This is sensless because EVERYONE is given a copy of this written process. Bob

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Speaking of passwords... Has anyone used AB's new feature about limiting where a person can plug in & make changes on a PLC? If so, do you like it or not? What's best? What's worst? We're still in the stone-ages here, but a new piece of equipment came in with 2 Micrologix 1100's, a ControlLogix processor and is completely outfitted in Ethernet & even a modem hook-up. (Ooooooh!!!!) We don't even have an up-to-date RSLogix 500 to be able to talk to the Micrologix let alone the RSLogix5K to talk to the ControlLogix - hence the need for the modem & dedicated phone line so the mfr can do all the work for us from his place & charge us a hefty maintenance fee. I'd love to get my electricans used to the idea of troubleshooting from afar. If everything was tied to a plantwide network, I could have an electrician take a couple of seconds to check that the problem wasn't a burned-out light bulb instead of a real process problem. (Totally common around here!) For now, all we can do is change the pilot lights to LED's and make that less of a problem. As for my network dreams, I'm putting in the plant's very first DH-485 network here in the next 2 weeks. At least I'll be able to plug into 1 spot on the tube mill & talk to any of the 4 PLC's (2 SLC 5/03 & 2 fixed SLCs) without running around. Then we'll get out the walkie-talkies, have the electrician go wherever the problem is & get it fixed quicker. <clinking glasses> Brilliant!

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At previous employer we had 11 plc's tied together. Started with a laptop but it was stolen within a couple of months. We ended up with a Desktop pc at a central location and the walkie talkies. What a pain.....I would be sure to have a laptop available for t/s'ing the problem area if needed.

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I agree, a laptop is still necessary for finding the right fix out at the machine. I'm working on getting comm ports to the outside of the control panels to make it easier to plug in. The whole key is accessability to the info. My wish is that if an electrician is at one breakdown and we've got several more calls at the same time that he could do triage on the others from his present location at the first breakdown. As it stands, management has taken the electricians off of more real breakdown calls to replace a simple blown lightbulb than I care to talk about. I don't manage the electricians (I'm still contract) so I can't tell the facilities manager which breakdown is more important... yet. I'm working on that. I know this is possible. It's been possible since the mid-80's when I was in college & doing my thesis on plant-wide networks. And it's so easy & tempting to buy a network module for each PLC and hang it on any kind of plant network. But I'm living in a bad 70's dream right now - almost all the machines go back to that era or before - where mechanical relay logic & 120VAC I/O reigns supreme. Yeesh! But going back to the original topic... I'm leaving all the processors I find in REM. I don't think the electricians will even notice. And if they do, it will be that teachable moment I've been looking for.

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