Plc and Laser Distance

Im semi new to plc's. What I am wanting to do is Used a laser distance sensor to control hydraulics on a machine. More or less a stop system. Is there a way where I could use a laser distance measure to turn on an output at a certain distance. I know you can take the 0 to 10 v and scale it in a plc but is there a way where you could input where you wanted it to stop like though an hmi. Say the cylinder is 20" on the scale fully retracted and fully extended it is 10" how would I turn of the the solenoid at 15" or be able to input where I wanted it to stop. Thanks

Welcome to the forum.

I would use a hydraulic position control card.
puts it where you tell it to go.

Is this constant pressure?

regards,
james

Thanks... Yea I have done some research on that and it is just for an old machine and just wanting to try something like this. I know it wouldnt be as accurate but yes it is constant pressure. In my mind I figure it would work similar to temperature setting for an oven more less shut off when you get to here. I just wanted to try something simple before I got into all the transducers and stuff like that.

Joshrice said:

Im semi new to plc's. What I am wanting to do is Used a laser distance sensor to control hydraulics on a machine. More or less a stop system. Is there a way where I could use a laser distance measure to turn on an output at a certain distance. I know you can take the 0 to 10 v and scale it in a plc but is there a way where you could input where you wanted it to stop like though an hmi. Say the cylinder is 20" on the scale fully retracted and fully extended it is 10" how would I turn of the the solenoid at 15" or be able to input where I wanted it to stop. Thanks

Click to expand...

Most laser distance sensors will have a scalable analog output (4-20mA or 0-10vdc) and discrete output. Set the output to the desired stroke based on the measurements and send that output to a plc.

One thing I should warn you about is that, depending on the resolution, vibration will cause your output to trigger up to + or - 1/4" of your desired stroke. Also for a fail safe, make sure you still have limit switches or proximity switch in place.

What type of valve do you have to turn the hydraulics on / off?

please explain your application in more detail.

regards,
james

You might need to scale it to the maximum range of the input card
20 32767
19 29490.3
18 26213.6
17 22936.9
16 19660.2
15 16383.5
14 13106.8
13 9830.1
12 6553.4
11 3276.7
10 0
Then you will use a compare function.
Some input cards have only 12 bit resolution, it all depends on what you got.

It should be fairly straightforward. Find a suitable laser distance sensor with a 0-10V or 4-20mA output, and wire that output to an analog input on your PLC. Set up some scaling in the PLC to scale your 0-10V/4-20mA into inches. On your HMI, set up a numeric input where you can specify the stop point, then in the PLC, if the scaled position value is less than the stop point input from the HMI, stop your ram from driving any further (but don't forget to allow it to drive back!).

As others have said, make sure you add backup stops in the form of proximity switches, or even better, physical limits. Best if these are Normally Closed switches, so that they are failsafe.

This is all a pretty generic overview, but hopefully it gets you moving in the right direction. If you need more specific help with a certain part of it let us know, but you'll need to provide some specific info on what hardware you're using.

Good luck!

Ok Cool so it is possible though an HMI. I think that what i will do is wire a relay in between the ram down solenoid and have this trip and maybe latch until up button is pushed. This will get me going in the right direction. What kind of affordable but capable plc are out there and what is the easiest and most supported programming software out there for learning purposes? I have a little cheapo plc now and don't know if it has all the functionalities as a normal plc...It's a click plc for automation direct

I have some other ideas and applications for this this stop system...Like band saw stop and chop saw stop not hydraulic side of it but just for a dro on hmi

What is the model number of your click. The newer ones will come with an Ethernet port capable of Modbus TCP. I would hook this up to an AdvancedHMI screen.
http://www.advancedhmi.com/

Regards,

Click Koyo is my go-to PLC for a simple application. Free, user friendly software and it's cheap.

I've never used a HMI with one before - for my work, if it's complex enough for a HMI it's generally complex enough for a higher spec PLC. But you can definitely put a HMI on it, and for something as simple as one value and maybe some basic start/stop controls I think it would be about all you need.

Yea It does have the ethernet port on it. So is that just software for the hmi I didn't see an actual HMI on the site but never the less looks easy to use. Maybe I'll stick with the click for testing I just know usually in electronics you get what you pay for. Im sure once I start i'll be asking more questions on the ladder logic lol