Ditron vs Sino...wich is better in your opinion

rwm · Sep 10, 2023

pontiac428 said:
That is the TTL configuration. I talked to Ditron this week, they said the heads can read either TTL or RS-422-A (8 wires plus shield). The difference is TTL degrades in long cable runs, where the twisted pair bucks noise. By long runs, I'm talking upward of a hundred meters.

They are lying. The internal wiring of the DB9 connector only has 5 pins in use. It can't "read" the RS-422 signal but it would be compatible with the basic TTL. Their customer service rep also spoke to an engineer who indicated that the expected accuracy of the 1um scale was worse than .002" per inch.

I'm curious what happens if you take a display that is expecting RS422 signal and give it 4 wire TTL from the read head? I assume you will see errors if it is expecting an absolute reference track?

pontiac428 · Sep 11, 2023

Robert, the board has 9 pin headers, so if worse comes to worse, I can try to complete the connection. The manual shows signal negatives.

rwm · Sep 11, 2023

pontiac428 said:
Robert, the board has 9 pin headers, so if worse comes to worse, I can try to complete the connection. The manual shows signal negatives.

You are correct on this. if you wired it, I wonder if the board would accept these inputs? I expect that it would and they just took a short cut since they know their head doesn't provide these signals. That is a great idea.
Do you know what would happen is I used a Ditron head (basic TTL) and plugged it into an Electronic display (which expects RS422 with reference.) I assume that would error since it would not see the check value from the reference track? I don't plan to do this, just learning.

pontiac428 · Sep 11, 2023