7I85S with TTL encoders

If i move the encoder the voltage changes from values 2.34 2.67 .... in both terminals. But the counts of the encoder doesnt count.

Maybe this line in the ini file is wrong?

CONFIG="num_encoders=1 num_septgens=2 sserial_port_0=000xxx"

Thank you!!

1.68V is a bad level (neither high nor low)

I would expect a low level less than 0.8V and a high level more than 2.4V
anything between these values it not a valid TTL signal.

You will have to move the encoder around to measure both high and low on the A and B pins
and dont measure when moving. That is, move the encoder a bit and stop, then measure
both high and low states of both A and B inputs.

Ok,

When the encoder is stoped it shows 2.4 V in both terminals, and while moving they change but it stops it show 2.4 again

I dont know why before was giving 1.6 V, because now is always and both at 2.4 V when stoped.

Thank you!

Edit:

It ´s random, now for example i have stopped it and has 1.77 in A terminal and 5.0 in B terminal....

Maybe im wiring wrong.

I have attached a jpg of how im wiring,

Terminal Encoder

1 Phase A
2
3 GND
4 Phase B
5
6 +5V

thank you!

You should be able to measure two states (high and low) on each ( A,B ) pin by jogging the encoder
and measuring. If you cannot get a valid high level and a valid low level on both pins, the 7I85 wont be able to read the signals.

The linear encoder i have is a FAGOR MODEL CT

I have read it is a TTL linear encoder, not a differential TTL encoder. I put you an URL:

www.fagor-automation.com/Products/Brochu...General_Feedback.pdf

It is described in page 20.

Thank you!

It ´s random, now for example i have stopped it and has 1.77 in A terminal and 5.0 in B terminal....

1.77V is not a valid low level so cannot work. Sounds like either a wiring error or perhaps the 7I85S inputs are set for differential mode.

EDIT: I just verified that a 7I85S and a 5i25 loaded with a 7i85sx2 configuration work fine for counting differential or TTL encoders.

Our test encoder has 0.4V low signals and 3.0V high signals.

If a TTL output device has a low level output above 0.8v or a high level output below 2.4V, something is wrong...

Hello,

When you say a 5i25 loaded with a 7i85s configuration, what do you refer to? Maybe im not loading correctly the driver of the 5i25.

How can i check it??

A strange thing to me, it is that the paralell port using 2 digital inputs is able to read pulses from the encoder correctly.


Thank you.

Edit: I think is a encoder problem, i have changed the reader and now read pulses better, i´ll continue this evening.

Thanks for all PCW.

Regards.

The driver (hm2-pci and hostmot2) is always the same, but the 5i25 firmware must match the daughtercard. If you ordered the 5I25 with the 7I85S, the correct firmware would have been pre-loaded in the 5I25. Also, the 5i25 should have a firmware label on the back that indicates what firmware it was shipped with. You can check the firmwares pinout by looking at dmesg after linuxcnc has been loaded:

sudo dmesg -c
linuxcnc &
(start linuxcnc config from chooser)
dmesg | more


All that said, if your have inputs that dont swing below 1.77V when low, this is a hardware problem not anything related to firmware.

Hello,

Now is working nice, i have to tune it. But it reads ok.

Mi firmware version is 38. Is that the one for 7i85s??

Thank you.

38 is the sserial version, and not really important.
The easiest way to tell if the firmware is correct is to look at the
pinout in dmesg and see if it matches your daugtercard and
what features you need.
Different configurations may match the same daughtercard, for example theres a 7I85S configuration with encoders and stepgens (7I85sx2) and one with encoders and PWMgens (7I85spx2).