Modicon 484, programming, replacement

[wogie 0]

A little background. I am completely new to PLC's and have been at the present employer two years. We don't have any experts at our company on PLC's. We have a molding line which operates with two Modicon 484 PLC's. We have just gone through a week of breakdown and thankfully are running again. The programs we are using are about 10-12 years old and when we had a breakdown we found a lot of equipmet that was supposedly 'somewhere' could not be found. We had experienced no PLC problems for at least a few years. Obviously the hardware is old but the previous owner had a habit of purchasing spare used equipment whenever he could find it available at auction, etc. We had two P180 monitors, one of which worked well enough for us to determine we had a problem with a 484. We also supposedly had two P190 tape loaders but we could find only one, and did not have the modem needed to connect to the 484 (J470?). Therefore we had to use a paper copy and manually type in the program through the P180. After struggling for several days at this we finally located some 'local' people who could help (except for contacting Schneider directly, whose rates seemed too high to afford, yes downtime is expensive too but I am not the owner). We found a 484 had gone bad and of the two spare 484's we had was not functional, but due to the help of the contractors they knew power supply parts which could be swapped that would get us running again. We also lost a J471 I/O expander. Questions: 1) My short range goal is to obtain one or two spare 484's, and a spare J471 (or two) and a J470 so we could talk to the unit. However, the P190's seem to be unreliable. The local company who helped us also made backups to the networks we have (there are about 63 in the program) including a backup to the other 484 which runs OK. Are there sources out there for inexpensive software which can be used to view and print out the programs? Also what should we have to reload the program, e.g. some software and the J470? 2) My longer range goal will be to upgrade and replace the 484 and I suppose the inputs. What advise can you give me in figuring out a long range plan? We don't want to spend a lot of money on the molding line because the PLC's we have work pretty good for us. We just want some more modern hardware and a better way to avoid downtime, in the event of a problem. This had our maintenance department stumped for a few days and caused me some sleepless nights. 3) What can I do to learn more about PLC's? Are there some good books you would recommend or some software to teach about it. I got the hang of how to enter the ladder logic with the P180 but it would have been nice to have some tutorial or something like that. Your helpful advise will be appreciated.

[Crossbow 295]

There's not much out there you will find for learning the relics like the 484. But if you wanted to learn a modern PLC, most PLC vendors offer training classes, some offer online classes, and there are numerous third party companies who offer PLC training. It really depends on your needs. I would recommend removing that 484 as soon as you can. I've removed 884 and 984 systems, so those things are ancient.

[Steve Bailey 118]

I agree with crossbow. The Modicon 484 dates back to the early 1980s. Although it was a popular model, it will get harder and harder to locate parts as years go by. Furthermore, any software that may have once been available to create documentation from the ladder file is now just as obsolete as the hardware. If you place any value on your time, spend it converting to a more modern, maintainable platform. With only 60-odd networks, it won't take a lot of time. Just about any PLC on the market today has a richer function set than the 484 did, so there shouldn't be any issues in translating the logic.

[wogie 0]

How should one go about selecting the right PLC to use? I mean, cost is certainly something to consider but since the functions used on the PLC are pretty standard for us will it be a matter of choosing a "good" brand, or ???? We don't buy PLCs frequently so I am at a loss to know what features to look for, etc. Thanks for your responses.

[Crossbow 295]

There's many reasons to pick one over another. But you need to choose based on the needs of your application. Do you need any kind of special program commands, communications capabilities, or anything else? Personally, I use Mitsubishi for most projects right now. Cost effective, but the software does leave a bit to be desired in some areas. I would find a good local integrator or distributor, and get a couple of quotes. Find the people you feel most comfortable with, who will stock spare parts, and provide the assistance you would need with the conversion. Most distributors will talk up whatever product they sell, but a good system integrator knows more than one line, and can help you find the right solution.

[Steve Bailey 118]

How much local support do you think you will require? If you think you can manage to get up and running with nothing more than telephone support, then Automation Direct will probably give you the most bang for your buck. Their prices are generally among the lowest, they have excellent phone support, but they do not have a network of local sales agents who can come in and help you over the learning curve. If you think you will need to deal with someone face-to-face, then you will probably be better off with with a brand that markets their products that way. Expect to pay more for that brand. To make a selection, invite the local distributors to come in and make their pitch. Select the distributor you feel most comfortable with and go with the brand they sell. The brand is less important than the relationship with the supplier and the competence of their support people.

[Rod_Hackney 2]

I would agree with the prior postings, find a local distributor that will support you. They may throw in some training for free if your going to standardize on their controls in your plant. You may want to consider the cost of programming software as well as the hardware, also, if they charge for technical support outside the original purchase. I worked on 484s when I first came into the field, I thought they were long since gone. Just amazing there are some still out there.