how to get Mesa THC values

Thanks John.

BigJohnT wrote:

The THCAD manual tells you where to get the scale offset number, it's different for each card a bit I think.

JT

The manual will tell you to look for a sticker on the back of the THCAD card. I forgot to write it down before mounting the card too so when I pull the card up I am going to make my own sticker and attach it beside the THCAD in the enclosure.

Hello everyone!

Having a bit of trouble with configuring the THCAD + 7i77.

Did the exact connections as in this thread (fout +- to enca+-) and 5v+- to the encoder's 5v+- on the 7i77.

I was expected to connect a power source to the THCAD input and see some output for the encoders's velocity.

Linked a variable input source to the THCAD 10, fed 2-3V to the THCAD and nothing happens. Velocity is 0, although the Encoder channel A appears as true.

Is there any other config that is missing? I've added the following lines in the machine_connections.hal:

setp hm2_5i25.0.encoder.03.counter-mode 1
setp hm2_5i25.0.encoder.01.scale -1

I know the scale is missing, however i don't understand why an output is not shown.

Could it have to do that the 7i77 gets the power from the 5i25 and has no external power supply? Although that does not seem to be a problem...

Should the encoder jumper be set for single ended or differential?

Am i missing anything? Do i need to add any other config? Can you please point me to a tutorial?

Already checked the forum and boards' documentation, did not really find an answer.

Thank you!!

tommylight wrote:

alex.statie wrote:

setp hm2_5i25.0.encoder.03.counter-mode 1
setp hm2_5i25.0.encoder.01.scale -1

Should the encoder jumper be set for single ended or differential?

encoder 01 or 03 ???????
Jumpers should be set to single ended.

I would tend to disagree here, When possible (and it is with the THCAD+7I77) you should always use differential signalling
so if you have fout+- wired to enca+- the 7I77 encoder channel connected to the THCAD should be jumpered for differential mode

Does the yellow LED on the 5V side of the THCAD blink faster with higher input voltages? (it should)

Thanks for the heads up!

It was indeed encoder 3, my mistake. However, that still does not solve it.

Also, tried differential and single ended. No luck...

PCW, the led blinks faster with higher voltage.

Any other ideas?

Are you watching the encoder 3 velocity pin with halmeter or similar?
Is encoder 3 count mode set to 1?
Are you sure you are connected to encoder 3 (encoders are 0..5)
do the other encoders work as normal quadrature encoders?
If you read encoder3 input-A pin it should read random high low values, does it?

Yes, watching the parameters with halmeter.
Yes, counter mode set to 1: setp hm2_5i25.0.encoder.03.counter-mode 1
Yes, it is encoder 3. Bottom one on second row. (0, 1, 2 are linked to axis)
Yes, the other 3 work as quadrature.
Encoder3 input A is True (bit value) and stays true no matter what i do to the input voltage.

1, you should use watch rather than show as show is just a snapshot of values
2. if encoder input A is stuck high that suggests a wiring error

Can you measure the voltage across A and /A at the 7I77?

Also you may need to turn off the encoder filter on encoder 3
if you are using the 1/1 THCAD mode