Mitsubishi alpha vs Allen Bradley micrologix

[stef]

Stef, what is it you’re wanting to do? It would help if we knew, as it is we’re just blundering around in the dark.

Software is a bugbear when it comes to the overall cost. I priced up a job for the foundry, I wanted to use Mitsubishi.
The management insisted I used Modicon “because all the lads understand Modsoft.” It was a bit of a pity really because the new Modicon range used PL7.
Mitsubishi software <£100, PL7 >£700.

Morning Tony,

it is just simple ladder logic, controlling conveyors for wash plants and test stands. The cabinets are full of ancient relays and timers (those pneumatic ABB types, obsolete for decades) leaving no room for expansion.
The plan is replacing them with PLCs. There is a big re-structure of the machine shop going on, with the PLCs we intend to increase reliability and also the possibility of easy expansion and integration with other machines. We are currently in the planning stage and ideally we should agree to one type of PLC. You might be surprised, but the management is leaving the decision to us :waving: But it has to be purchased from RS (because of the next day delivery I suppose)
In fact, when it comes to technology they are very approachable (cos they haven't got a clue) so I want to make it as cost effective as possible, it has to be easy and reliable. That is why I started this post, get different views and opinions.

Hope this helps.

 

[Knobhead]

One reason I liked the Modicon TSX micro is they have 5A relay units. I was having to switch furnace contactors in and out frequently. The contactors are made by Telemecanique to switch high voltage capacitive loads so no chance of changing them. To add to the fun the PLC controlled the LV and HV breakers. I had 110V AC and 30V/130V DC all switched by the same unit.
You can have up to 64 5A relays so it made my life easier when dealing with older gear. You’re not limited to 64 O/P it’s just the maximum of relay units 4 x 16 way that can be used.
http://static.schneider-electric.us/docs/Automation%20Products/Programmable%20Logic%20Controllers-PLCs/MKTED204012EN.pdf

Programming for ladder is reasonably simple, one thing I found very useful was the ability to use drum controllers. I used them for the shut down and earthing sequence also the maximum demand control.
The earthing procedure had my sphincter twitching the first time I tried it. The incoming 660V 2.6MW single phase busbars were shorted to earth and then each capacitor bank switched to earth. Once proved it became an automatic feature.
The maximum demand control was fun. Linked in to the works trend system so that if we were getting near our MD limit the furnaces would power down from around 1.5MW to just 55KW. At the end of the restriction they powered back up again, adding compensation for heat loss. All done in ladder.

If it’s an on going project the software cost is spread out over several units so really doesn’t enter in to it.

 

[Darkwood]

I don't have great experience across the ranges i tend to settle for Siemens Logo or Schneiders Zelio soft2 although i have had a lot of problems uploading and downloading the logo in the past and it comes down to that its written under the windows pro package and as most computers and laptops are shipped out with a chopped down version of this it can cause allsorts of issues when using a USB lead to link your PLC to your computer...

Im currently getting to grasps with Crouzet logic soft M2 but overall if your wanting to create such a simple program then id be inclined to opt for a PLC with free software and a good priced PLC that way you can upload and practice on the software before you choose.. or simply stick to what you already know.

From experience with cost, ease of use and logic functions I edge to Zelio as i find the Boolean function block a God send to design your own logic Gate but i dare say this is a common function to many ranges out their but from experience not all.

 

[Robotstar5]

If you're going to be fitting a number of machines with PLC's consider types with the option of communicating with others or a master PC, Modbus, Devicenet, Ethernet, etc.

 

[Knobhead]

Only really used ModBus and the old Modicon PeerCop system. Some of the main Modicon 984’s were a nightmare using both systems. Trying to keep track of what went where became a game.

To add to the fun 984’s and TSX/Magelis use reversed bit patterns. Bit 0 on TSX is bit 16 on 984’s, even the bit numbering was different. TSX 0→15, 984 16→1, they’re both Modicon!

The first time we linked a 984 to a TSX I was working with a French engineer, there were some glorious **** ups. Neither of us knew about the bit patterns, add the language difference and things went a bit haywire. It was funny though.

 

[Robotstar5]

To add to the fun 984’s and TSX/Magelis use reversed bit patterns. Bit 0 on TSX is bit 16 on 984’s, even the bit numbering was different. TSX 0→15, 984 16→1, they’re both Modicon!

Was it Modicon that had a BROT (bit rotate) function block in the software?.

 

[Knobhead]

Yes BROT, it made life easier with the ModBus connections.
The DX functions made the 984 a versatile piece of kit. EMATH blocks made my brain hurt.
The beauty of Modsoft was being able to put quite comprehensive descriptors to registers. If you had implied registers for a function then the descriptor would point you to the right place. Took time to do, but was worth it in time saved later.

 

[i4Automation]

Reliability will be be about the same have a look at the current rating for any relay outputs and ensure this covers your requirements. As mentioned have a look at software costs, programming cables and support. It might be worth looking outside the box and saving yourself some money with a Jazz unit from Unitronics, software is free and it uses a USB programming cable, similar to that found on many smart phones or cameras.

 

[stef]

Reliability will be be about the same have a look at the current rating for any relay outputs and ensure this covers your requirements. As mentioned have a look at software costs, programming cables and support. It might be worth looking outside the box and saving yourself some money with a Jazz unit from Unitronics, software is free and it uses a USB programming cable, similar to that found on many smart phones or cameras.

Aren't you those guys who sell the PLCs with HMI integrated? I think I still have the catalogue somewhere. Could you mail me a price list, please? :waving: I lost the contact details!

 

[Knobhead]

Thought something seemed familiar.