Inductive Proximity Sensor with a One-Shot Output?...

I'm using an Automation Direct SureServo drive, and it has an 'odd' homing routine. Depending on the state of the home sensor when the HOME routine is started, it ends up at 2 different final locations. See MY POST at the A-D forum for details.

I think the simplest 'workaround' would be if the home sensor could generate a one-shot pulse when it turns ON. This way, the servo drive would always home to the same location. I was wondering if anyone knew of an inductive sensor with this logic built-in. I'm currently using a 12mm tubular sensor, but any size or shape would probably work. I know I could just use a timer with a one-shot or 'pulse' output, or a dedicated one-shot module, but this panel is pretty cramped, so I'd rather not add additional components. If I could simply replace the sensor, that would be ideal...



-Eric

with one or more relays you could prevent the homing command unless the Prox is off.
If needed, then allow the homing in the FWD only or hold it on when the Switch is made.
the logic and relays can both be small.
At the worst case - use a smart relay.

I agree Ian on his point here.

At the worst case - use a smart relay.

Click to expand...

Or, another way to take care of this problem, is use the control system (plc if is connected to)that's controlling the Servo drive to handle this issue. All you need is 2 I/O (the prox and the output)

Would a signal conditioner work?
http://www.balluff.com/NR/rdonlyres/6217D732-E60D-4915-9BD5-0AD38FE0A71A/0/KT_SignalAdapter_EN.pdf

controlled said:

Would a signal conditioner work?
http://www.balluff.com/NR/rdonlyres/6217D732-E60D-4915-9BD5-0AD38FE0A71A/0/KT_SignalAdapter_EN.pdf

Click to expand...

Perfect solution! I knew there MUST be something out there. These might come in handy for other applications too. Thanks, controlled!...

As far as the other suggestions... I can probably accomplish this with just one additional relay. The home sensor is wired directly to the servo drive, but the HOME command comes from the PLC. I can probably just wire the home sensor through the NC contacts of a relay. When I issue the HOME command (or slightly before), I can turn on this relay for a short period of time. If the home sensor happens to be on, it will be ignored long enough to move off the sensor.

My only concern with Plcwill's idea is signal delay. I/O response time and scan time may affect repeatability. In this application, I'm homing at a slow speed, so it probably isn't an issue. If you read my post at A-D's forum, you'll see that I was originally using the index mark on the encoder for home. This was extremely accurate.... until they changed gearbox ratios on me...

Thanks guys!... :site:



-Eric

Can these Balluf units be used to create a one-shot? Turck has a similar product (Smart Plug) but I don't believe they can create a one-shot(could be wrong).
http://www.turck-usa.com/Products/Sensors/Smart_Plugs/

Oops! Wait a minute... Those Balluff signal conditioners can only be setup as an on or off-delay timer. I would need a one-shot (sometimes called 'pulse') output...

A good find regardless! I can think of a few other applications where they will be helpful.

Oh well... I guess I'm back to adding a relay.



-Eric

EDIT: I see you're paying attention, Bob!...

Eric,


This is probably $$$ but I found this Omron unit that has a remote inductive prox that wires into an amplifier. The amplifier has the ability to give a one-shot uputput. It would probably be cheaper to shoe horn some tyoe of logic into your cabinet.
http://www.omron-ap.com/product_info/E2C-EDA/index.asp

Thanks, Bob. I stumbled across those during my initial search (Looks a lot like a Keyence photoelectric amplifier!) They would work but, as you said, they're probably beyond this project's budget. A cheap relay and a spare PLC output will be more cost effective...



-Eric