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Messages - MN300

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41
General Mach Discussion / Re: Manual pulse encoder & mach3
« on: January 18, 2022, 08:27:52 PM »
The MPG is a nonessential option so you can take a chance on the cheap route, especially if this is for hobby use. If it dies you can get along with the regular jog until you find a better one.

42
General Mach Discussion / Re: Manual pulse encoder & mach3
« on: January 18, 2022, 07:56:12 PM »
The item in your link looks OK but is pretty expensive.
I searched ebay.ca for "100ppr Manual Pulse Generator" and found many items. This one claims to ship from the US.
https://www.ebay.ca/itm/301581285751?hash=item4637a53977:g:cfEAAOSwPhdVG-QU
It's the four terminal type but you don't need -A or -B.
Lack of details in the listings always makes it hard to know what you are getting. It would be good to have one with mechanical detents so it stays put when you're not turning it.

43
General Mach Discussion / Re: Manual pulse encoder & mach3
« on: January 18, 2022, 06:34:57 PM »
I see two things wrong in your description of the encoder operation, the output only goes to 2.5V and the readings are different when you change direction.

Here is a video testing the same part number encoder.  https://www.youtube.com/watch?v=NvHlbB1eWSs
Look for two things as you watch. When the model number is shown the 2nd line is a different format than yours. video=NO D20180915 your photo=NO:YCJ 2021.04.02. Does the difference mean it's counterfeit or did they change the numbering scheme? Possibly it means it has different options.
About a minute in when the dial is being turned you can see when it stops the mechanical detent holds it exactly on an index mark.

 The 2.5V reading instead of the 5V I expect could be you're turning too fast. If you stop on the detent and slowly advance one click at a time you should see either 0V or 5V.
The output pattern of a quadrature encoder is
A    B
0V  0V
5V  0V
5V  5V
0V  5V
etc.
Note the state of either output changes every 2 clicks.

The C10 boards inputs are CMOS. They expect an ON signal to be above 3.3V and an OFF signal to be below 1.6. The actual threshold where it decides whether an input is On or OFF is somewhere in between. If the IC on your board has a threshold a bit below 2.5V, and your measurement is correct the input would work - barely.

To summarize, either the output voltage of your encoder is too low or it's not a quadrature encoder.
Craig's suggestion to buy from a known good vendor may be the best solution.

John

44
General Mach Discussion / Re: Manual pulse encoder & mach3
« on: January 18, 2022, 01:37:42 PM »
I have found general information about your encoder series but nothing that says what options yours has. If it does have open collectors it should work correctly with pullups.
If the encoder does test OK connect +A and +B to the inputs of your choice and configure the software to match.

45
General Mach Discussion / Re: Manual pulse encoder & mach3
« on: January 17, 2022, 06:05:39 PM »
The outputs of a quadrature encoder should be on 50% of the time and off 50%. This is not what I see in your video, they are at 0V most of the time with a brief excursion to about 2.5V. The most I saw from +A was 1.25V but that might just be your meter not reading quickly enough. You should be able to find positions where the output stays at the higher voltage.

We really need more info on your encoder, does it have a model number?

Your encoder may need pull ups. If you don't have resistor in the range of 1 to 10K on hand you can use your C10 board for a test. Configure it as shown in this diagram to provide pullups. Which encoder output goes to which input isn't really important as long as they see a pull up from an input. No 25 pin port connection is needed, just power and the encoder.

46
General Mach Discussion / Re: Manual pulse encoder & mach3
« on: January 17, 2022, 01:26:07 PM »
In the video the encoder  is being turned too fast for the meter to settle so I'm not sure what I'm seeing. When you measure from +A to -A I would expect to see some negative values but didn't.
Try measuring from each output to ground (0V). If you turn slowly enough you should see values near 0V and 5V. All 4 outputs +A, -A, +B and -B should look the same.

47
General Mach Discussion / Re: Manual pulse encoder & mach3
« on: January 16, 2022, 10:31:57 PM »
Just the +A and +B outputs can be used in a single ended system like a parallel port interface as long as ground noise is not too great. -A and -B would be unused.

The typical 5 volt differential encoder has two complementary outputs per phase. When +A output is on (5V)  -A is off (0V) and when +A output is off (0V)  -A is on (5V).  If you attach the positive lead of a meter to +A and the negative lead to -A the meter will read either plus 5V or minus 5V depending on the state of the output. The difference between the two states is 10 volts compared to the 5 volt swing of a single ended output. Not only does a differential signal give you twice the noise margin but but also cancels common mode noise.
Logic outputs don't actually go all the way to ground or the power rail so the voltages in the example above would be slightly less, say 0.5V and 4.5V.
 
https://www.digikey.com/en/articles/understanding-encoder-output-signals-to-aid-optimum-device-selection#:~:text=An%20encoder%20that%20contains%20a,exact%20opposite%2C%20or%20complementary%20signal.



48
General Mach Discussion / Re: Mach3 tachometer help
« on: October 15, 2021, 03:34:57 PM »
Quote
Testing in a power supply with Pin 1 to +5V and pin 2 to GND, I read 2.3V on pin 3 with no magnet. When a magnet is introduced I read 0V.

When testing the OH137 a pullup to a positive voltage should be connected to pin 3. If you have a resistor somewhere in the range of 1K to 10K connect it from +5V to pin 3. The output should switch from 5V to near zero.

Quote
On the PMDX-126 board with no OH137 connected to it, just measuring the terminals, I read +12.5V where the blue wire is connected, and +4.5V where the brown
wire is connected based on the picture.   Shouldn't the terminal with the brown wire read 0V with nothing on it?

I can't comment on this because I can't see which terminals those wires are connected to. Whoever installed those wires may not have used to the standard color convention.

Here are some check of the PMDX-126 you can do.

With the meter negative lead to a GND terminal and the positive lead to +5V you should read  +5V.

With the meter negative lead to a GND terminal and the positive lead to 12U you should read about +12V. It's unregulated so it could be several volts higher than 12V.
 
With the meter negative lead to a GND terminal and the positive lead to an input you should read a positive voltage. The manual doesn't say if the inputs are referenced to +5 or +12.

49
General Mach Discussion / Re: Mach3 tachometer help
« on: October 15, 2021, 12:16:29 AM »
Your voltage readings don't make sense, I am wondering if you have the OH137 wired correctly. I can't tell from the photo where wires are connected.

Please check your wiring.

OH137 pin 2 should connect to a GND terminal, the nominal color for this is blue. Your photo is showing black but of course it will work regardless of color as long as the correct two points are connected.

OH137 pin 1 should connect to a +5V terminal, the nominal color for this is brown. All voltage readings should be made with the negative meter lead connected to a ground terminal. You should measure 5 volts with the positive lead connected to OH137 pin 1 at all times.

OH137 pin 3 is an open collector output, that's like a switch to ground. You will read 0 volts there until it's connected to something that pulls up that line. That something is the input number of your choice.
First check the voltage at that input with nothing connected to that terminal. The manual doesn't say what it should be, please let me know what you find.

Connect that input terminal to OH137 pin 3, the nominal color for this is black. The input voltage should change to 0 when the magnet is sensed.

50
General Mach Discussion / Re: Mach3 tachometer help
« on: October 14, 2021, 04:17:59 PM »
The transistor on the diagram is a leftover option from the examples in the manual. Just wire the OH137 as shown with no extra transistor.

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