7i77 encoders not working

I have 3 axis mill with differential encoders and trying to read encoders with 5i25/7i77 boards. Board is set to differential encoders. All encoders are wired correct and work when pluged into enc0 or enc5 on 7i77. when any encoder is pluged into enc1, enc2, enc3, enc4 then not work. Use halscope to look at inputA and inputB on encoder inputs when I turn axis screws with hand. enc0 and enc5 show square waves for A and B, that is correct. enc1 shows square wave on B and zero on A. Enc2 shows square wave on A and zero on B. I think enc3 was zero on A and B, and enc4 was square wave on A and off-on square wave on B. Am only pluging one encoder in at a time, so 5v power not issue. Am now using debian 8 with preempt 3.18 kernel, but get same when tried linuxmint 17.3 and lmde2 with preempt rt. This is brand new boards from mesaus.com.

As a first guess I would say bad/wrong/loose cable between 5I25 and 7I77
or bad 5I25/7I77 power jumpering (mismatch between cards)

Another possibility is wrong 5I25 firmware

I have two 5i25/7i77 cables. one from mesa and other 1284 compliant. tried both and no change.

board jumpers are
5i25
w1 down
w2 down
w3 up
w4 up
w5 up
7i77
w1 left
w2 right
w3 right
w4 left
w5 right
w12 left
5v from external power

I ordered 5i25 board from mesaus.com with 7i77 firmware. I hope I got what I ordered. Attached is mesaflash output but nothing says 7i77. Why would enc0 and enc5 work good and others do not? I am working on amd64 system, but tried on 32 bit system and got same results. Is there way to look at encoder A channel at lower level then hm2_5i25.0.encoder.02.Input-A to see if channel is reading encoder? I have digital oscilloscope to use if needed to read inputs.

thx.

OK that looks like the correct firmware and if they are IEEE1284 cables, that should be right

Have you checked the encoder output voltages in all states?
Measure across A and /A then B and /B

These should always be >2V or < -2V across the pins in all quadrature states
any voltage close to 0 in any state indicates a wiring or encoder problem

I will check voltage across pins, but if encoder works in enc0 and enc5 and not when terminal cap is moved to enc1-4, not that mean that encoder and wiring is good and either software or board is bad?

Your problem does seem odd to me. I don't want to second guess Peter, Could we see your config files just to check for anything obvious. (but I don't know of anything that might cause these symptoms.)

Could a problem with how the encoder inputs are muxed be the source of this?

Most encoder issues we have seen tend to be wiring issues.
Marginal signals (due to wiring or wrong encoder type)
may work on some inputs and not others.

Mux issues tend to cause obvious even/odd troubles

A bad 5I25 or 7I77 is possible but of course all 7I77 encoder inputs
are tested and all 5I25 I/O pins are tested so if either are bad its something
that changed since shipping

I am unaware of any software issues with the encoders

I measured the voltage between A and /A on x axis encoder going to enc0 and voltage is 0.2 to 0.6 volts. Same for B and /B. You are going to tell me the wiring is wrong. I double and triple check wiring. According to original schematics I have encoder wire A going to A, encoder wire /A to /A, etc. Maybe original schematics are wrong, but how do i tell what is right? Is a way to test encoder wiring? I also see what someone told me was pull up resistor going between A and 5v, B and 5V, and index and 5v. Could that cause problem? If wiring is wrong, how come enc0 and enc5 work? Very confused. Help would be appreciated.

Are you sure your encoders have differential outputs?

It sounds like either they

1. Dont have differential (line driver) outputs (they are TTL single ended encoders)
2. They are not powered properly

You might check the voltages without being connected to the 7I77 (and its differential termination)

The encoders are
OPTcoder
Sumtak LBL-010-500
DC 5V 160 mA
8901-0039 500 p/r

wiring is:
8 5V
7 0V
1 A
3 B
6 Z
9 Shield
2 Anot
4 Bnot
5 Znot


here is website and pic of my encoder www.galco.com/repair/Sumtak-Daido/LBL-010-500
I was told they were differential, but not sure. They only get power from the enc0 connector and it is at 4.96 vdc.

Do not know how to check voltage if encoder is not connected to 7i77 because no other wires with power connect to encoder. Do you mean disconnect only A and /A and B and /B, and then check their voltage?

Still come back to same question -- why they work on enc0 and enc5? Can enc0 and enc5 be more sensitive to pick up low voltage signal and enc1 - 4 not able to see low voltage?

thx for help.