Balluff BOD63M Sensors

Has anyone used a BOD63M sensor for distance measurement? I have set two of them up (BOD63M-LB04-S115)in different applications and both of them go wonky before they get to the specified 6000mm distance. In one application, the sensor is monitoring the movement of a hydraulic cylinder. With a tape measure the cylinder is only moving 38", but the Balluff is showing ~43-45". I've verified the scaling in the PLC (SLC 5/05). It is configured for SCALED FOR PID and I'm using a SCP block with 0/16383 as INPUT MIN/MAX and 200/6000 as OUTPUT MIN/MAX (The Balluff sensing range is 200-6000mmm). I am taking the SCP output, subtracting the offset of how far the sensor is from it's target and then dividing by 25.4 to get inches. The reading is right at 1", off by about an inch at 20" and 4-8" off at 38".

The other application is similar...looking at the back of a machine that is moving away. Starts out tracking right with an encoder on the machine, but at about 1/2 max travel, it reads much higher than the encoder.

I know what you dealing with????

Ok , most of the time these sensor are smart sensors???
Well what I am trying to say is . there ranges are programmable.

Depending on whether or not ? They have both digital and analog i/o.
You should have a way to set parameters inside the sensor. the minimum and maximum ranges . such as as1 as2 . it scales that range to 0 to 10 or -4 to 20 . then you can also use your scaling with parameters to tune it in? also the further the distance the larger the error. and most of these large distance sensors (range) do not have but a 15mm repeatability ..such as the Ab45cpd laser . if you dont set up points in the laser itself . I believe it defaults to 0 to 600 mm which its range is 200mm to 6000mm . so if you use the real life measurement and created
your scp based on this info , but fail to set up the laser its sensing range points . then this could have bad results.. I hope this helps

Smart...but not too smart

These are pretty good sensors and they do have and analog output as well as two digital outputs. According to the documentation that I got with the sensors (and downloaded from the Balluff website, there is no programming involved. These sensors are 200-6000mm, 4-20mA with no programming needed. The only adjustment is a potentiometer for the switching distance of each of the digital outputs.

Here is the link to the documentation. Haven't had much chance to work on this due to other responsibilities recently.
http://www.balluff.com/Balluff/Documents/manuals/832764_DE.pdf

Just a little tweaking

Turns out that I just had to adjust where the laser was pointing...as it got out further in travel, I was getting the red "fault" LED which indicates that the sensor is not getting good enough signal for accurate measurement. I adjusted the aim a little so that the red LED stayed off through the whole range of travel and now it is measuring really well.

Lasers are cool but have to be right.

A lot of times what I do is actually lie to the plc about the range that the sensor is actually reading? I always read the the minimum voltage reading and then the maximum voltage reading.

And then I scale the laser based on this info . try it in its optimal settings between 200mm and what ever the maximum distance is your needing to read

Working great now

Thanks for the idea...getting the sensor to stop erroring out was the ticket...it is working great now.