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PLC I/O Recommendations

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I'm curious as to your PLC I/O preferences and would like to get some feedback for the forum users. What I/O platform do you use? What do you like about it? What was your driving decision for your selection? What products have you tried? Thanks Deb

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The answer will largely depend on your control platform. What PLC are you planning to use?

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Thanks for the reply Allen Bradley, Siemens primarily. Sometimes Beckhoff and Mitsubishi . I know there are a few universal platforms out there that support many open networks and was looking for some candid feedback on some implementation experiences. Thanks

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Assuming you mean remote I/O, the first thing you'll want to figure out is which network to use. Unfortunately, if you're trying to stick with the same I/O regardless of the PLC type, you'll have to jump through some hoops. Each of the brands you mentioned have their own preferred network that is very easy to set up... on that controller. Here's my experiences with various brands. In the Allen-Bradley world, I've dealt with Flex I/O over DeviceNet and Point I/O over Ethernet/IP. I prefer the Point I/O, but that may simply be because it was Ethernet/IP and extremely easy to set up in Logix 5000. DeviceNet is a little more complicated. In the Siemens world, I have only physically used their remote I/O in training, though I've helped spec it on some projects. My experience with Siemens is that while they're frustrating to program, their networking is about as simple to set up as it gets. My first Siemens job, I was up and running with an S300 and five drives over Profinet in about 15 minutes! In the Mitsubishi world, CC-Link is the preferred network, and there are a couple of different flavors depending on what you're trying to put on the network. There's a version strictly for I/O, as well as one that is gigabit Ethernet and can handle both intelligent devices and simple I/O. I haven't used their remote I/O, but CC-Link in general is fairly easy to set up. I haven't used Beckhoff, but I believe they are heavy into EtherCat, which is their Ethernet-based network. If you're trying to pick a universal I/O, you can always get add-on cards to deal with different networks, but you'll have to check cost and availability for each brand. For example, don't pick CC-Link or EtherCat, since you would have to turn to third-party gateways to use them with all platforms. DeviceNet or Ethernet/IP are more likely, but tend to be more expensive. Profibus and Profinet are more available and more cost-effective; I know you can use them with Mitsubishi and Allen-Bradley at any rate. For a truly universal network, you're probably best looking at Modbus and Modbus TCP solutions. While it isn't the preferred network for any of the brands you mentioned, it's one of the most widely supported and there are a large number of manufacturers that make Modbus remote I/O. Some of the Siemens and AB controllers will even talk Modbus TCP using available function blocks, with no add-on hardware.

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For new projects I recommend Profinet. It uses "standard" routers, switches, wireless and Cat 5 or better cabling. Is deterministic. Easy to configure and troubleshoot. Has a huge number of manufacturers I/O to choose from giving you the ability to select the best I/O for your job instead of being stuck to what a small group has to offer with you needing to design around their short-falls. YMMV

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Many vendors do not support ProfiNet (like Mitsu, not sure about Omron). Mitsubishi always pushes CC-Link Omron on their newer NJ Series uses EtherCAT

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I would certainly avoid DeviceNet. It's our number one downtime problem.

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Thanks for the input, it is appreciated

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Try to stay with Ethernet. It will be easy to check, it uses standard equipment that can be found even in supermarkets (when you’ll be in a set up and somebody will cut a communications cable it is nice for it to be Ethernet). In my case I’ve been using Beckhoff for at least 18 years already and I can say it is wonderful. - It works without problems (only changed one card in all those years). - It is extremely fast (the cheapest digital IO module has a clock frequency of 5ms which is giving you 2 reads in a normal 10ms PLC cycle). - All the E-BUS IO cards are suitable for all Beckhoff controllers. (Most of them and with all the new ones). - Being able to plug different CPU’s into the same IO boards’ gives you the option to separate properly the physical layer from the software one. I’ve worked with Siemens, Allen Bradley, Telemecanique and other strange things, but I love PC-based solutions as they offer the best of the PC (HMI, communications…) and the best of a high level controller (as no PLC in the market will have a processor as powerful as the ones in modern PC’s). PS: Oh, and Beckhoff offers you a good number of fieldbuses to communicate to almost anything… My two cents! ;) Edited by Joan Murt

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I use Mitsubishi FX3U-16MT/DSS (8 DI/8 DO) with a FX3U-ENET-P502 for (almost) all my projects. The ENET module is communicating with a Crevis I/O node that's equipped with all the digital and analog I/O I need. When using the ENET-P502 ethernet module am I using Modbus TCP/IP for I/O communication. The have several different network units for Modbus RTU, Profibus DP ........ If you haven't heard of Crevis, take a look at their website. I normally use the FnIO S-Series from Crevis. Don't think I had more than one faulty I/O-slice in the last two years. (The faulty one might be a result of a colleagues curiosity) Normal usage is a couple of hundred I/O slices per year, so I'd say the quality is good to.

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CREVIS newer G-series. We use CREVIS to replace WAGO equipment primarily in robots.

Approximate table of functional analogs:
750-881    GN-9372    PLC adapter with CoDeSys V3.5
750-333    GN-9222    Network adapter PROFIBUS
750-354    GN-9386    Network adapter EtherCAT
750-306    GN-9212    Network adapter DeviceNet
750-307    GN-9261    Network adapter CANOpen
750-310    GN-9231    Network adapter СС-LINK
750-430    GT-1238    IO module 8DI universal type (Sink or Source), 10RTB
750-1400    GT-123F   IO module  16DI universal type (Sink or Source), IDC20
750-1405    GT-12DF    IO module 16DI universal type (Sink or Source), 18RTB
753-440    GT-1904    IO module 4DI, ~240V, 10RTB
750-536    GT-2318    IO module 8DO, Sink, 24Vdc/0.5A, 10RTB
750-530    GT-2328    IO module 8DO, Source, 24Vdc/0.5A, 10RTB
750-1501    GT-221F    IO module 16DO, Sink, 24Vdc/0.3A, IDC20P
750-1500    GT-222F    IO module 16DO, Source, 24Vdc/0.3A, IDC20P
750-1505    GT-225F    IO module 16DO, Sink, 24Vdc/0.3A, 18RTB
750-1504    GT-226F    IO module 16DO, Source, 24Vdc/0.3A, 18RTB
753-540    GT-2734    IO module 4DO, SSR, =24V/2A, ~240V/2A, 10RTB
750-453    GT-3114    IO module 4AI, 0~20, 4~20mA, 12 Bits, 10RTB
750-468    GT-3424    IO module 4AI, 0~10, 0~5, 1~5Vdc, 12 Bits, 10RTB
750-460    GT-3704    IO module 4AI, RTD, 10RTB
750-451    GT-3708    IO module 8AI TC/RTD, IDC20
750-493    GT-3901    IO module 1ch 3ph ~500V/1A, 10RTB
750-553    GT-4114    IO module 4AO, 0~20mA, 12 Bits, 10RTB
750-559    GT-4424    IO module 4AO, 0~10Vdc, 12 Bits, 10RTB
Use the information at your discretion, perhaps it will be useful.

The actual link for description files for EtherCAT, Profinet and others: Downloads

 

 

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