Proximity Sensor

I've just finished building and I'm running through the commissioning procedure.

I've update to the 0.65e firmware.

My proximity sensor is giving readings the other way round to the instructions - away from anything its a high number arund the 280 mark, and with a piece of paper near it goes down to around 100.

Therefore, when I do the axis homing the Y axis crashes into the end by the motor.

I've triple checked the wiring etc, have I done something wrong or has there been a change to the wiring I'm not aware of? (ie I read on another thread about a wiring change for the sensor but it wasn't clear what plugs go on what pins if this is the case).

Many thanks in advance, I was so looking forward to having it working!

If you are getting a reading as high as 280 when the sensor isn't near anything, then either the sensor is not working, or not connected to the correct pins (check the blue wire in particular, it should be on the 9th pin from the end in the lower row), or you have a lot of sunlight or incandescent artificial light that is messing up the reading (does the reading drop if you put black paper under/around the sensor head?).

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Thanks for replying so quickly!

The blue wire is on pin 9, and I've not tried darkening the room nor a darker colour paper - I'll try that when go back to the office later this afternoon and report back.

I've been back and tried it in a darkened room with black paper - with the sensor away from anything its reporting between 230-280, with the black paper right up near it's 0-30.

Is this a dodgy sensor that needs to be replaced?

In a room with little or no sunlight and only fluorescent or LED artificial light, you should get a reading close to zero unless you have a reflective surface close to the sensor. Sunlight and halogen light can cause a large reading. Tungsten lighting also has an effect, although less severe.

Are you certain that it makes a difference whether you have the black paper near the sensor or not? If the Duet pin is effectively disconnected from the sensor, you will get semi-random readings.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

I had a similar problem on my new machine and the the same firmware. I tried reloading the firmware and the problem went away. I do not know why and I still have other problems but that one went.

Thanks for the ideas, I'll have another go in the morning after reloading the firmware, and also test the continuity of the cabling with a meter.

I've reflashed the firmware twice and checked through the cabling thoroughly, I'm still getting a reading of around 280 away from anything and it drops down to as low as 10 with a black surface near the sensor, so it looks like I'll need to change the sensor.

The printer was a present from my sister (bought from RS), I don't have the receipt and she's on holiday for a couple of weeks :-(

Can anybody advise on the procedure for getting this sensor swopped? Would it be via RS or through RepRapPro?

JuzzyD, PM me your address, as you can have my sensor. You wil have to solder the wires in, or use your old connector pins if you want to keep a connector on it.
I got sick and tied of the problems with the sensors working then not being accurate dependant on it being sunny in Banglerdesh or where ever, that I did away with it, and use microswitches now.
They always work, have never let me down, and only need resetting if I take the HotEnd out. I'm in Kent,Uk, so your only a stamp away.
Regards,
Kim..

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Please send me a PM if you have suggestions, or problems with Big Blue 360.
I won't see comments in threads, as I move around to much.
Working Link to Big Blue 360 Complete

You have PM! :-)

I received another sensor, very kindly sent to me by KimBrown, but this time I'm getting a fairly static reading around the 80 mark. Swopped back to the original sensor and I'm getting similar readings I had originally.

Is this looking like an issue somewhere else? Could anything else be affecting this?

I'll be seeing my sister tomorrow and will then have the receipt so I can then contact where it came from and go from there...

JuzzyD: Sorry, I didn't see this thread earlier. Can you post a picture of your wiring, on both the Duet and the proximity sensor (a close up of the latter would be good to check it's soldered okay), so we can check the wiring?

Usually it's a case of getting the wiring correct - if you could check this again, and where it connects to the Duet board, that would be good. From left to right on the proximity probe, it should be blue, black, red; then check on the Duet that the black and red are the correct way around on the pins next to the extruder motor, and the blue wire is on the 9th pin from the right on the bottom row - refer to the wiring diagram here: [www.reprappro.com]

For a good fit onto the proximity sensor, cut off the two small tabs that stick out on the housing; it will sit much better on the pin connector.

Then, check that you have the following line in config.g: 'M558 P1'. You can also type this in as a manual command in Pronterface. This turns the probe on. Check the sensor readings with G31.

I assume you have done the commissioning steps: [reprappro.com]
There is also a troubleshooting guide: [reprappro.com]

However, it's also possible that there is a fault with the sensor. There is some good examples for testing on the ormerod forums.
You can check the voltages on the proximity board; see: [forums.reprap.org]
And visually inspect the board for the correct resistors; see: [forums.reprap.org]

Finally, it's possible it's a problem with the Duet board, and the Analogue to Digital Converter in the chip is faulty. There's not much we can do about that apart from replace the board, though again, a visual inspection of the board is a good idea, to see if there are any solder bridges or other shorts may be causing the problem. We are about to release a new version of the firmware, 0.78, on which the sensor pin is being moved (the current pin is used for other functions on the multi-extruder expansion board). So you could update this firmware, which is in our 'test' branch at the moment. Then move the sensor wire to the 6th (rather than 9th) pin from the right, on the bottom row, and see if that works.

You can email me on support at reprappro dot com for direct communication, if you need parts. We'll need your full name and address, and it would be good to have your RS order number, but as the machine was a present, it's not entirely necessary.

Ian
RepRapPro tech support.

Ian, Justin sent me a PM saying he's just noticed that the sensor was bent at 90'.... So I think he's sorted it now....
I sent him the sensor off my machine as I wasn't using it.

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Please send me a PM if you have suggestions, or problems with Big Blue 360.
I won't see comments in threads, as I move around to much.
Working Link to Big Blue 360 Complete

Hi Kim

Ah, yes, that would give a bad reading too! Another one to add to the list...

Ian
RepRapPro tech support

Sorry for the late reply, only just got back this evening.

The sensor given to me by Kim has been working but occasionally doesn't stop the Y-axis at the end, I'll try a bit of white tape on the little ledge that it senses against to make sure it gets a definate difference in reading.

I'll have time tomorrow to go through the rest of the commissioning and hopefully do a print so fingers crossed!