Axis's creeping away...

[nickcornilsen]

My appologies - after re-reading what I wrote, I see I wasn't very clear.

I disconnected one encoder from Kanalog. I energized the encoder as it was designed.

I put a 480 ohm combined resistance across the + and - wires of the A channel, and left the B channel open.

I then measured the voltage drop across the 480 ohm resistance. (simulating what it would see when connected to Kanalog. This voltage was either 50mV, or 1.5V depending on where the encoder was.

I also checked the voltage across the + and - wires of the B channel. This voltage drop was 4.96V, or 50mV.

There are 1K pull ups installed between the + wire of each channel and the 5V source. There are no pull ups or pull downs on the - side of any channel.

I can try putting a 1K pull up on the - side of each channel and see what that does.

The encoders are original to my tree 325 - Sumtak LBL-030-500. Just like the ones in this Ebay auction:
Tree Journeyman 325 Optcoder LBL 030 500 5V Sumtak LBL030500 | eBay


I've search for information on these encoders before, couldn't find anything.

[Al_The_Man]

Well evidentally the LBL come in 3 flavours, but RS420 differential not one of them.
5v,12v & 15v, with Open collector, Open collector complementary, and TTL Line driver.
So at 5v, yours could be TTL?
Unless they mean the TTL Line driver is RS420?
You could pop the cover off to see what driver IC is used?
Al.

[TomKerekes]

I'm guessing these are open collector complementary.

I think adding 1K pull ups to both + and - signals should work.

Kanalog uses a AM26LS32ACD differential receiver which only needs to see +0.2 and -0.2V to switch.

Repeat the test you described after adding pullups on both sides and you should then observe (measuring across the 480ohm resistor) the voltage toggle between +1.4V and -1.4V.

Regards

[nickcornilsen]

I'm guessing these are open collector complementary.

I think adding 1K pull ups to both + and - signals should work.

Kanalog uses a AM26LS32ACD differential receiver which only needs to see +0.2 and -0.2V to switch.

Repeat the test you described after adding pullups on both sides and you should then observe (measuring across the 480ohm resistor) the voltage toggle between +1.4V and -1.4V.

Regards

I'll give that a try!

[nickcornilsen]

Ok, so I put a 1K pull up to the A_ and B_ channel wires. Now when I move the axis, it toggles between -1.47 and +1.47.

I'm thinking this is what I want to see right?

[TomKerekes]

Yes!

[nickcornilsen]

Yes!

Excellent. I thought it was, so I picked up the 1K's I'll need. I'll plug 'em in tommorrow and get a run at the next hurdle!

Al_The_man, Tom, Zen Hacker, I appreciate all of your help on this!

Hopefully there's enough info on here that someone else having this issue can search and save them the trouble shooting!

[Al_The_Man]

Like I mentioned in post 22, when I am in doubt with an unknown encoder, popping the cover off and noting the transmission IC can usually fill in the blanks.
Al.