DerStrom8
Super Moderator
I made a small PCB to interface the cable to the sensor, That way I have tons of room..
Hmm, well a PCB may not be an option here, but I see no reason why Veroboard wouldn't work. Thanks for the idea Ian!
Follow along with the video below to see how to install our site as a web app on your home screen.
Note: This feature may not be available in some browsers.
I made a small PCB to interface the cable to the sensor, That way I have tons of room..
Apart from the 25ma sink detail the actual (output) nature is not shown.
Just as the term 'Quadrature' when used with an encoder should not be used to describe the x4 technique of using the 4 distinct edges to increase the resolution.The whole PPR/CPR has been a bit confusing though. I understand PPR ("pulses per revolution") really should not be used for quadrature encoders, yet I frequently see it anyway.
The opto encoder I have selected does not have the detent. I settled on the EM14A0D-C28-L032N (rated for 1M+ rotations, which is far better than the 200k for the ones with the detent. The original mechanical ones were rated for 100k).
I was thinking that was a standard way of describing the operation of that type of encoder...?Just as the term 'Quadrature' when used with an encoder should not be used to describe the x4 technique of using the 4 distinct edges to increase the resolution.
Max.
Yes, I am aware that the parts that create the detent are what wear out the fastest. I understand it will still operate, but the user won't feel the detents easily after they wear out.For clarity...
The optical switch part is rated for 1e6+ in both, the detents are optional but are the parts which are rated for less.
The push switch in yours is also rated for less (100k), but should be more than adequate.
I was thinking that was a standard way of describing the operation of that type of encoder...?
After discussions with the engineers who will be using the device these encoders control, we decided to use the Avago HRPG-AD32#56C instead, which is a detented encoder (datasheet: https://media.digikey.com/pdf/Data Sheets/Avago PDFs/HRPG_Series.pdf )
The whole PPR/CPR has been a bit confusing though. I understand PPR ("pulses per revolution") really should not be used for quadrature encoders, yet I frequently see it anyway.
After fitting the encoders in to the new board and hooking it up to test, we're seeing some issues with inconsistent increments per detent, and if it's spun very quickly it actually seems to register as going backwards. We never had this problem with the old mechanical encoders. Any thoughts on what would cause this?
I did notice quite a bit of flux residue on the boards, and the encoders had been sitting out of their packages for a while on a desk. Any chance they were damaged by ESD?
Thanks guys,
Matt
if it's spun very quickly it actually seems to register as going backwards. We never had this problem with the old mechanical encoders. Any thoughts on what would cause this?
Have you put a scope on the encoder output to verify it's dropping pulses?
Could be the encoder is working just fine but your uC isn't reading them fast enough or your denouncing method is too slow. Are you using interrupts or polling normal inputs?
Unfortunately this is a fully built unit already and I can't really do any hardware hacks or breadboarding with it. I may be able to get a scope probe (or two) in somewhere to monitor the waveforms though.Hi,
Sometime a test tells you more than anything else can.
To find out the encoder pattern you can connect LED's or LED's connected with CMOS buffer gates. Turning the shaft reveals the pattern.
To find out the speed however you'd need to connect a dual channel scope to the encoder and turn the shaft and watch the output on the scope.
I should be able to tell you. This device effectively syncs a strobing backlight with a camera shutter to catch "video" (or more accurately, a series of still images) of drops of liquid being ejected at a set frequency. The encoders select the frequency (usually in the tens of kilohertz range) and the delay of the camera shutter with respect to the backlight strobe. The encoders must increment the frequency by 500Hz accurately each detent. Right now it is very inconsistent, and if spun up quickly the frequency jumps around and even goes down.Can you say whether this encoder is being used for data entry, in which case missed steps may not matter. Or is it being used where missed steps will matter, such as a commutator? Nevertheless, 5 rpm is pretty slow and is pretty conservative for debouncing.
Can you say whether this encoder is being used for data entry, in which case missed steps may not matter. Or is it being used where missed steps will matter, such as a commutator? Nevertheless, 5 rpm is pretty slow and is pretty conservative for debouncing.
John