question about what device to use to track linear motion of drill head

[Daveinarmstrong 0]

I am using a drive to move a drill head left and right approximately 12 inches and i do not have access to any of the rotary internal parts of the drive so i need to track only the linear motion of the drill head. is there such a thing as an inexpensive linear encoder that my Mitsubishi FX2n could read the pulses from through one of its inputs. the speed of the drive is 0.50 in/sec. thanks in advance for your help.

[kaare_t 155]

Since you have movement in both directions I think you will need an encoder with A/B phases. How else can you detect which direction the axis is moving? In that case I don't think you can use the FX2N since it does not support A/B encoders on any of the standard inputs. If I were you I would use a FX3U, you can connect an A/B encoder directly to the first inputs of the base unit. As to the encoder itself you can use any A/B encoder of your choice. Linear controls isn't my speciality so please correct me anyone if I'm wrong....

[gleblanc 1]

What kind of a budget do you have, how accurate do you need to be, and how much electronics do you want to do? You can get linear scales in 12" length, and something like the DRO-550 to give you position. You could link the BCD outputs of the DRO to digital inputs on your PLC, and get absolute position that way. I'm sure you could find something to interface directly with the PLC, but it's likely to be a lot more expensive. I'd think you could get the scales, DRO, etc for around $500. Greg

[Daveinarmstrong 0]

i have a budget around $1500. Now I am thinking of using a DRO.