choosing a plc

hi every one
i have to use a plc on a large goods motor and was wonderiong if any one can tell me what the main considerations would be Voltage will be 24 vdc 7 inputs and 5 outputs per unit and 4 units being controlled by 1 plc

There are lots of things to consider. IF you could give a better description of what you are trying to do we can give you a better answer.

Details to include: Power available, number of functions you want to control, existing systems currently in use. What type of control voltage you plan on using. Do you need to interface with other equipment.

THat is just a start there are lots mre details used in deciding which PLC to use.

kev23,

Welcome to the forum.

Clay B. said:

There are lots of things to consider.

Click to expand...

One important item is: Do you have any PLC's on site, and do you have any software for them?

Edit: Kev23, Can you describe what a "large goods motor" is? I'm curious.

kev,

You will want to consider the following:

It will help if you provided a list of your I/O devices to the forum. From your initial post, there will be four of everything. So, unless this is different, you need only list your devices once.

Based on your information you will need a total of 28 inputs / 20 outputs.

You will need to determine the type of I/O you will require.

Digital I/O can be either AC or DC. From the statement regarding your power, it appears that you will be using all 24 VDC.

With regards to the outputs, you can use either relays or transistors. Much will depend on your load and freqency of switching. The more you switch, you may want to consider the transistor output in that it should last longer then a relay. The difference...A relay uses an arm and contact for completing the circuit. The transistor has no moving parts for making contact to complete the circuit and turn on the output.

You will need to determine your budget for your project. Your budget will include the controller, software and any devices you will require, to accomplish your application.

Software will depend on manufacturer and will range anywhere in price from Free to over $1000.00.

Of note, we provide a free programming software package. www.entertron.com/software.htm

You will next want to research controllers that meet your requirements.

We offer two different products that will satisfy your application I/O requirements with a few left over.

1. SK1600-RIC configured as 32 DC in / 24 relay out - www.entertron.com/sk1600ric.htm

2. Elite-2000 configured as 32 DC in / 32 DC transistor out - www.entertron.com/elite.htm

You will also need to determine if the devices you are driving can be handled by the outputs directly from the PLC or if you will need to use interposing relays that will be turned on by the PLC but will bear the brunt of the load from your devices.

There are many manufacturers you can choose from. Here is a link to the forum's list - http://www.plcs.net/chapters/links.htm

Hope this information is able to get you started.

God Bless,

Welcome to the forum Kev,
another consideration you should look at is your network. since you have 4 systems, are they close together? If you shutdown the main PLC all 4 systems will shut down. Maybe you need 4 small PLC's. What do you think?

no i dont need 4 plcs
i have got to do some research to find out what the maximum amount of memory is on a plc, what the maximum number of I/O's you can have on 1 plc and what the processor speed is ?

i dont have to decide what plc to use all i have to do is find out what the maximum number of I/O's that can be put on a plc, what the maximum amount of memory you can have on a plc and what the processor speed is
i do not have to take any thing in to consideration