Replacing Advanced Motion Controls "brush type 12A8 with "Axcent" amplifier

My question goes out to all, what is the encoder channel? I have read the 7i77 manual, have I missed the area to read? What is the "encoder channel" ? My question is related to setting the hal scope to see the "square wave" produced by the encoder count? Need to prove the encoders are working.


all help warmly welcomed
many thanks!

As to the exact definition of that phrase, it is a little hard to say without the context of the text you are referring to.

But to get to the root of your real question. In Halscope you will want to look at the hal pins "hm2_5i25.0.encoder.nn.input-a" and "hm2_5i25.0.encoder.nn.input-b" (replacing nn with the number of the encoder input you want to use such as 00,01,02...)

PS: Remember Halscope can only sample these signals at the the servo thread rate. So try not to turn the encoder at a rate that might output pulses faster than about 500/sec, or you will get misleading results.

Todd, Many, many thanks for your help. I have used the pin selection you suggested, no motion or change of any kind. No DRO. Through process of elimination, the last component is the 7i77 card. To edit this to accept a different encoder at different location like TB4 (encoder 03 & 04). Is this how I should be thinking about this?

I don't understand, earlier in this thread you posted plots that obviously showed that you had the encoder connected to the 7i77 and DRO feedback working in Linuxcnc. What changed? You should not have removed any of the encoder wiring to the 7i77 card. We only suggested adding wires from the A and B terminals of the 7i77 to the encoder A and B terminals of the servo drive, to enable Velocity control of the drive and make tuning them easier.

Todd, I had a project that I was not confidant of some of the parts because they were proprietary or had no documentation. Nearly all of that has been replaced or the data is verified.

Quote from Todd
"We only suggested adding wires from the A and B terminals of the 7i77 to the encoder A and B terminals of the servo drive, to enable Velocity control of the drive and make tuning them easier."

This would be a set of leads going under the same screw (location 1 & 4, TB3; both 00 & 01 encoders) on the encoder plug on the 7i77 card (A and B terminals) to AMC (P1-Siginal Drive) pin 6 (ENCODER-B IN) and pin 7 (ENCODER-A IN) as per (sheet 4 of 9) of AB15A100 manual.

This would be a set of leads going under the same screw (location 1 & 4, TB3; both 00 & 01 encoders) on the encoder plug on the 7i77 card (A and B terminals) to AMC (P1-Siginal Drive) pin 6 (ENCODER-B IN) and pin 7 (ENCODER-A IN) as per (sheet 4 of 9) of AB15A100 manual.

P1 (pin 1 on signal connector) based on your attached drive pdf is a 10v output! Why connect to that? Your encoders are getting power from the 7i77 5v. If anything you would share ground on pin 2 (signal ground) if that is the correct pdf.

Correction, I just read that wrong. coffee not kicked in yet LOL... you are just calling out the P1 connector and not actually connecting to pin 1, if I understand correcly?
You may still need to connect ground pin.

Todd, Many, many thanks for your help. I have used the pin selection you suggested, no motion or change of any kind. No DRO. Through process of elimination, the last component is the 7i77 card. To edit this to accept a different encoder at different location like TB4 (encoder 03 & 04). Is this how I should be thinking about this?

How are you moving the table? I suggest manually moving the table with the servo powered off to see if the dro counts.
I would connect your new encoder to the 7i77 1st to see if you can get it to read in then make the connection to the drive.
If you're switching to another encoder connection on the board make sure the hal and ini are configured correctly.

OT-CNC, Many thanks for your help. I have tried to move table, no change to DRO. Currently new encoder is connected as per diagram. I am close to getting the x axis with wire under screw at encoder 00 (TB3) going to driver pin 6 and 7, plan to try x axis only, at this time.

Many thanks!!

I have plugged power supply in to the wall and released e-stop, the software was in process of boot up and as soon as releasing e-stop x axis started jerking and red LED on AMC driver was blinking, so I quickly reset e-stop. Open to ideas. Many thanks!

Edit: I will copy (save as starting point) and edit the .ini & .hal files with the "find and replace" (this is what I recall, maybe not correct) to use TB4 (ENCODER 4 & 5 and TB5; DRV 4 & 5 ). Use 04 and 05 in the edit process. What else should I be thinking about?

Many,many thanks to all for the your help!

Many thanks, for all the help! I have edited the .ini & .hal files with the "find and replace" go from 00 to 04 & 01 to 05. The error is shown in the pic. This included the new locations TB4 & TB5 on the 7i77 card with the "jumpers" to the left. The wires under the screw on pins 1 & 4 (to provide additional input) are off for now. The LEDs on 7i77 are ok with exception of red LED that usually goes blinking (I think) after establishing connection.

Many thanks

Edit: similar error message.

In Linuxcnc versions 2.7 and older.
The axis numers can not be skipped and must be in order.
X axis = AXIS_0
Y axis = AXIS_1
Z axis = AXIS_2

Not sure how you ended up with the Axis numbering in your files.