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

[WobblyHand]

How would I hook up an 8 wire read head to a Display that wants 5 or 6 wires? Can some be unused?

Just connect the positive wires of the pairs. Cap the negative wires.

Edit: Make sure you obviously connect power and ground!

 

[Boswell]

Actually, 90+% of the time they are compatible, especially over short distances like 3m. Unless you have a huge amount of electrical noise in your shop, and long distances, the ttl outputs are fine. I have a vfd on my lathe and ttl dros and there are no issues on my glass scales.

Not sure I agree. My understanding is that RS-422 standard is current driven, not voltage while TTL is voltage. I agree that for short distances you could use TTL instead of RS-422 but I don't see a situation where you can have an RS-422 device on one end of a cable and a TTL device on the other end and the are able to communicate. It is possible that devices that say they are RS-422 do not entirely follow the standard, save for TTL. just a bit of trivia but RS-232 is commonly called out as a communications standard but is very rarely implemented per the standard and yet it is stalled called RS-232

 

[WobblyHand]

RS422 is not a current driven standard. It's voltage. You may be confusing this with a 4-20mA current loop. I'm an EE, (now retired) and worked on many of these systems. A ttl output can be read by RS422 input. An RS422 output can usually be read by a TTL input.

RS422 was developed for longer distances and higher data rates than RS232. It has better noise immunity because it uses differential pairs for the signal and is quite useful for industrial settings. That being said, it's more expensive and rarely needed in a home shop. I'm using ttl because it's good enough. I'd only recommend it for high electrical noise situations or extended lines.

Of course, you can always spend more.

I'd use high speed optocouplers if there's some real noise and ground isolation issues over RS422, but that's me. That way any ground loop is severed. My stepper motor driver for my ELS is optoisolated. Depending on the size and installation, ground at one location may differ at the other location. This can mess up signaling. An optocoupler can solve this problem, but it requires different wiring. It's not hard, but you do need to wire it correctly.

 

[Boswell]

well my bad. I did a quick search on RS422 standard and was sure I saw reference to current loop similar to 4-20mA but now I can't find that so I apologize for my misleading post. Even with the understanding of RS422 being a voltage driven standard, I am surprised that it would interface with TTL due to differential pairs. But I am no EEE so I bow to @WobblyHand knowledge.

 

[WobblyHand]

well my bad. I did a quick search on RS422 standard and was sure I saw reference to current loop similar to 4-20mA but now I can't find that so I apologize for my misleading post. Even with the understanding of RS422 being a voltage driven standard, I am surprised that it would interface with TTL due to differential pairs. But I am no EEE so I bow to @WobblyHand knowledge.

No worries. RS422 can handle being driven by only a single line. For maximum noise immunity, it's better to use the pair. For short cable lengths, like the typical 3m long cables, you can get away with receiving a single TTL signal. The RS422 receiver chips are designed to accept single ended TTL signals without damage.

 

[rwm]

Upon further though, my Ditron heads have 6 wires using pins 1,2,3,7,8,9. This is not exactly what Yuri shows on his site but I'm guessing it is RS422 without reference.
I basically have 2 options now:
I can get a Magna Slim scale from DRO Pros for $258 and try to rewire it.
I can return the Ditron to China for $150 shipping cost and theoretically get a refund. They agreed to this but I have no idea how much hassle this will involve.
Then I can buy a 2 axis package from DRO Pros for $1500. I would trust this setup but I would lose RPM indication.
Totally confused about which way to go!

 

[mksj]

You can get a 3 axis ES-12B with magnetic scales for around $800 including air shipping. You need to specify the lengths and 1 micron head on the X axis. Numerous forum members have ordered from them, I have yet to hear any issues. PM/QMT has the MX-200 (EL-750) with two magnetic scales. As far as shipping back to China, my experience has been that if USPS is it could be months to get back, to China and the costs are can be horrendous. You would probably do better to sell it locally. RPM is no big deal, you can add one for $20. If you other scale has the same degree of error then I would probably get a new DRO setup, if it is OK then maybe just the scale and deal with the scale interface. Given the number of problems with the Ditron DRO's, I would not recommend buying one, let alone ordering one from China.

Easson ES-12B LCD digital readout package including 3 linear magnetic encoders

3 Axis Easson ES-12B LCD graphic digital readout package with three magnetic encoders. The encoders offer a very compact profile size and can be cut to length to custom fit the machine being installed. The package is suitable for mills up to Bridgeport 42" sized machines or 30" between centre...

www.machine-dro.co.uk

MagXact Magnetic MX-200L 2 Axis Lathe LCD DRO – 8×40 Inch Scales – Precision Matthews Machinery Co.

www.precisionmatthews.com

https://www.amazon.com/DIGITEN-Digital-Tachometer-Proximity-Switch/dp/B00VKAT8A2

 

[rwm]

Wow!!! So basically PM is underselling DRO Pros on the exact same package by $500??? The only issue is I need the Magna Slim Scale on the Cross slide. I'll give them a call and see if they can do that.
BTW-You guys are awesome for helping me through this. Ya'll are a great resource.

 

[rwm]

OK. So here is the plan for all of those waiting in suspense. I ordered a 1um slim Magna Slim scale from DRO Pros. I want to make sure it will physically fit in the space. I think it will.
I also ordered this DB9 connector set to make an adapter.

Hopefully I can figure out the wiring and get this to work with the Ditron DRO. I happen to have and EL400 Display that I can also plug into if needed. This gives me a lot of options I think.
I should mention; I called PM. They only sell kits which include the scales. They do not have the Magna Slim so I cannot go that route. Also their DRO displays are software specific for lathe or mill. So you could not put a 3 axis and later put in on a mill. Well you could but it would not have features for milling.

 

[rwm]

@ycroosh - Any thoughts on my Ditron read head with 6 wires? I do not see this variation listed on your website? Is it RS422 without reference?
@WobblyHand ?