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Combined HMI-PLC experience.

Combined HMI-PLC experience.

Combined HMI-PLC experience.

I am looking into updating the control panels we use for our OEM Mixing systems.
We currently have panels made up of push buttons, relays several red-lion process controllers and VFD.
There seems to be a variety of HMI / PLC combo units capable of multiple I/O and analog inputs.

Does anyone have experience with any of these units. I would like to keep cost down but not sacrifice maintainability by plant maintenance resources.
Like to stay away from obscure and proprietary software etc.

RE: Combined HMI-PLC experience.

I have a lot of experience with these and recommend them:
There are several sizes and price ranges all use the same I/O, drivers and software. Very reliable. The only down today is that for Ethernet I/O it is only Modbus TCP/IP. Profinet is coming I am told.

RE: Combined HMI-PLC experience.

Do you have a plant spec? What is the majority of the HMI/PLC in your plant? Problem with not having a plant spec is any OEM can just use what they typically use and send that to you. Now you have a basket of HMI/PLCs that you need a different softare package and etc... to keep around in case of a problem.

RE: Combined HMI-PLC experience.

The problem with "Plant Specs" is that they are always out-of-date and too restrictive. Whereby you end up with old controls on your new equipment or only the cheapest your "Spec" dictates instead of the best for your new equipment.

RE: Combined HMI-PLC experience.

Just about every PLC requires proprietary software to program. What you need to look at is the combined cost of the hardware and the software. BTW setting a standard for manufacturer and platform is a good idea. Typically PLC platforms last 10 to 15 years.

RE: Combined HMI-PLC experience.

My only problem with combo PLC/HMI units is that from an end user perspective, if you lose one, you lose them both. If they are separate and for example the HMI dies, (which happens more often than the PLC) the PLC programming remains intact and you can replace the HMI separately. Even if the HMI is obsolete or there is new incompatible firmware and you have to start over, it's just a matter of making your tags match the PLC program. If the combo unit dies, you start from scratch 100% and if the unit has gone obsolete, you as the end user may have to take on system responsibility to get it up and running. I know, not necessarily a concern for an OEM, I'm just venting a little on the overall practice of using those.

"You measure the size of the accomplishment by the obstacles you had to overcome to reach your goals" -- Booker T. Washington

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