typical hardware counters can talk with plc?

[syed misbah]

HI, Everyone, im working on small project, that's basically product counter. The current setup at our factory is the hardware counters that are located at the product lines. Now. Our management wants the product counts per day from various product lines to shown at one monitor. I was thinking to use sensors signals simultaneously to the hardware counter and as well to the plc digital input. please let me will this work. Also if you know any hardware counter that can talk with plc will be more helpful.
Im beginner in field of plc, would appreciate all the inputs from all of you guys.

 

[Saffa]

What sensors are being used to count your products, and how do they interface with these "hardware" counters (i.e. clean contact closure)? draw us a picture.

In principle, yes you should easily be able to use the same signal to drive a PLC input. It looks like in your application is reasonably simple, so I probably wouldn't go down the road of replacing your counters with something you can query via MODBUS or some other protocol, it wouldn't be worth the cost?

 

[syed misbah]

Hi saffa., we are using the proximity sensors either pnp or npn.the sensor is directly wired to hardware counter. Im away from my pc, but ill try to upload the drawing later.

 

[inst_tech]

Assuming the voltages being used on the existing equipment are "normal"(!) then you could use a cheap Siemens Logo and HMI. More than ample for what you say you require but if things change will give you scope for modifications. If you want to gain experience in the PLC field you could always ask your employers to go for an S7-200 as you'll probbaly learn more. The Logo is the cheap(ish) easy way!

 

[Clay B.]

Variables you are going to have to watch out for:

1) Mixed voltages: all of your counters would have to be on the same voltage supply. Or else you would need to make them that way. You can not mix power on a PLC card. even though you make have 16 individual inputs they all share a common.

2) Distance: How far is it from one counter sensor to another. If you are going into 1 PLC this could be an issue as well.

3) Transfer data: once you have this data on a PLC or more than one PLC how do you plan to put it together and send it to your display.

Look at your system again and see how everything is currently wired and post those details. Take in account all of the counters. Also besides the display being in one location, how is it supposed to be displayed. This will effect what HMI you buy.

 

[brendan.buchan]

What sort of counters are you using?

Do they have any on-board communications eg. RS232/485?

We are using a Red Lion Datastation to get the PV and set the SP of some counters via RS232. You could also do this with a Red Lion G3 HMI.

You could then set up a page/user interface on the Red Lion that you can view in a web browser to display the values, or you could then send the values to another PLC via ethernet.

It all depends on what hardware you already have.

 

[wimpiesplc]

It's probably not that difficult to "also" count on the PLC but don't forget the counter gets reset at the end of the day. what need to happen then, at the PLC?
But I read "products per day" well.. if your hardware counter counts well enough, the input signal of the counter should be sufficient to count at the PLC also. but then you have to keep track somewhere about that "day"
When that management wants to put money in such things, why not ask for some HMI? It doesn't have to be that costly but it makes it easy to replace the hardware counter in the first place. I think it's better to have one counter in the PLC then duplicate one in hardware.