Opinion on my new master/slave setup

Hi!

Today we have turn-key machines that go worldwide and no slave/master option. My customer has indicated that they want to develope some kind of master/slave cabinets because it's common that they sell for example six machines to one end customer and they want to be able to reduce the price of the electrical equiptment.

Today we have a cabinet that consist of HMI, PLC and a VFD. There are also ofcourse power supplys , relays, contactors and motor curcuit breakers. But there isn't alot. You can say that a good 1/3 of the cabinet price is HMI and PLC.

In my thoughts I want to make the cabinets as they are today, only removing the HMIs from the slaves. I still want PLC in my slaves so that I will not be dependent on the master. The only thing the master does is that it will supply a HMI for the slaves. By doing this I will save the price of the HMI on my slaves. This is in my opinion a good way of ensuring that the machines will run even if something falter. I will connect the machines with ethernet and I can have 32 slaves /master

The second alternative would be removing the PLC from every slave. Thus making the master cabinet more equiped and the slaves depend on that the master is working. By doing this I will save the price of the HMI and PLC in every slave. But I will have a more expensive master cabinet and very critical that it work. This would be connected with regular cabled wiring and I figure that I can have 4-5slaves / master if I dont equip the master with several PLCs.

What are your thoughts?

Another option would be to use remote I/O in the slaves instead of a full PLC.



-Eric

I'm sorry I forgot to spec the cabinet. The cabinet is equiped with a MicroLogix1400 and I don't think that this can have a remore I/O feel free to correct me because I haven't used ML1400 and AllenBradley PLCs so much.

You can easily add remote Modbus I/O with Micrologix 1100 / 1400. With 1400 you will still have access to a serial port. All you need is 1763-NC01 break-out module.

Yea, we use the 1763-NC01 to the VFD. But what AllenBradley product can I run remote I/O with my ML1400?

I've used this:

http://www.automationdirect.com/adc...r_I-z-O_Network_Interface_Modules/T1K-DEVNETS

Along with various I/O like:

http://www.automationdirect.com/adc...inator_I-z-O_Discrete_Input_Modules/T1K-16ND3

I've also used the same type of product with DeviceNet adapter connected to SLC 5/05 PLC, but it will be more expensive because you'll need a 1761-NET-DNI adapter.

I have an Advantech Adam 6066 (http://www.advantech.com/products/GF-5WLT/ADAM-6066/mod_e256cafc-36dd-4740-86a0-d7e53b5c4ddf.aspx) sitting on my desk that I'm going to play with for the same purpose over the next week or two.

I'm sure there are many other manufacturers that offer similar remote I/O products over Modbus

With Modbus adapter, you simple set up MSG instructions to read/write from the remote I/O.

Thanks alot for the tip, I will look into it if it suits our need. In this specific project I think that maybe we can't use it because we are using the Rockwell Connected Component concept and we also like to have the same brand in atleast the PLC,HMI,VFD and communications because it is easier with support and fault finding But your tips are very usefull for our more special cabinets that we have nearby. Thanks alot!

It sounds like an inferior design to me. the only advantage is saving a PLC or HMI?

Independent and identical systems are way better than coupled!

V0N_hydro said:

It sounds like an inferior design to me. the only advantage is saving a PLC or HMI?

Independent and identical systems are way better than coupled!

Click to expand...

With the solution with PLC in every slave it will never fail if the HMI crash because you don't need the HMI to run the machines. They are automatic and HMI are only for manual mode and statistics and fancy stuff. The price of the HMI is 25% of the cabinet price. True though that it is always better with one HMI on every machine.

Fully agree with V0N_hydro.
If HMI is used for manual mode, why should operator walk anywhere to switch modes or change settings?
You did not specify your HMI model and its communication interface. If it is PV+, just look for a less costly one.

These Machines are turnkey machines that is often fit together, meaning that you place for example six machines together and you can clearly see all of them from everywhere in the room. 99% of the time, the machines are in i automatic mode and HMI is just for manual (service) and statistics. So I guess that is why they are talking about having a master slave setup. Today they are having trouble selling the cabinets because they are to expensive. Sometimes the customers choose another company and sometimes they descide to build the cabinets themself (meaning alot of trouble for my customer since they have to troubleshoot machines with unfamiliar and sometimes faulty cabinets). I guess one way of doing it is what you said, try to get a cheaper HMI. It is and PVP600 7" panel (I think) running on ethernet.