Dro display

Hi all, my milling machine dro recently decided to stop working. The dro was already installed when I got the machine a few years ago and is an expensive dro pros unit. I have ordered a Chinese display unit but after installing it I am unable to get the display to read the scales. I have tried altering various parameters but nothing seems to work. Does anyone have any knowledge of these units, I am wondering if maybe it is not compatible with magnetic scales.

Hello Cliff,

You need to tell us a lot more information about the old system . Make, model number etc and about the new display unit (presumably a generic two or three axis Chinese system?

Andrew.

Hi Andrew, the old system is a dro pros el400m with electronica EMR B scales and the new display is a sons-v3 Generic Chinese unit.

Incompatibility is a distinct possibility. My search engine can't find a 'Sons-v3' DRO, but if it's one of the generics it probably works on single-ended 0 to 5V TTL. The Electonica EMR scale I found is up-market; it has a differential RS422 interface, like TTL but designed to reduce noise and work over much longer distances. It does this by signalling between plus and minus,a complication that might be too much for a generic head. And the EMR scale probably requires the head to provide positive and negative power, whilst a simple generic head only provides positive, and possibly at the wrong voltage. Check the head manual - any mention of RS-422 or differential signalling?

The wiring of plugs and sockets varies too. Although 9-pin D connectors are common they don't necessarily wire the same pins together. For example, the new head might provide power correct for the scale, but on different pins - the existing cable is incompatible. Therefore Machine-DRO and others sell conversion cables allowing scales and heads from different makers to be mixed, but choosing the right cable requires the specification of both ends.

Can you provide technical details of both devices, or hyperlinks to what you have? As Andrew said, Make, Model Number, Manual etc. More the better - it's all in the details.

Saving money is the big advantage of buying a generic DRO off the web. Disadvantage is lack of support if they don't work! Firms like Machine DRO are good because you ask them to supply a head compatible with an existing named scale and they recommend one, plus conversion cables if necessary. Disadvantage - cost.

If all else fails cheapest fix may be to replace the scales with a type known to be compatible with the head. A head compatible with expensive anti-noise scales might be pricey. But check the manual first, generic electronics play catch-up with the last year's wonder-gear, and a new cheap head might be capable if configured and wired correctly.

Dave

Sorry it’s an sns 3v https://www.alibaba.com/product-detail/SNS-3V-DRO-digital-readout_50044821519.html

https://www.dropros.com/Electronica_Milling_Machine_Digital_Readout.htm#Electronica_Magnetic_Scale_2_Axis_Mill_Kits:

these are the links for the new and original

Machine DRO do an adapter cable for Electronica " Console adapter cable - Allows an Electronica display console to be used with M-DRO and Easson encoders " This implies that there are wring differences. Obviously this in the opposite sense to that your are looking for in that you have Electronica scales and a newer console. For £15 it may be worth investing one to take apart and check the wring differences, but I wouldn't expect Machine DRO to provide any support.

**LINK**

Good news, bad news...

Good news: The SNS-3V info mentions it supports EIA-422, so in theory it should work. It's probably a cable problem, easy to fix if you know how. (Unfortunately, the 422 standard only addresses signal requirements, and leaves choice of plugs and sockets wide open.)

Bad news: I can't find anything on the web explaining how the cable should be wired at either the Head or the Scale. And I can't think of an easy way of working out from the devices themselves how they're wired. Maybe someone else has a suggestion, or knows what the likely combinations are.

Stuart's M-DRO converter might work but it's head to scale rather than scale to head. It will work if the pins are wired symmetrically, but not if the wiring happens to be illogical.

Not all is lost. Maybe the pin-outs are described in the paper manuals, or they mention a website? Also, I'm not a top-shot internet searcher; it needs a certain flair to spot clues and think up smart search terms.

Dave

Edited By SillyOldDuffer on 06/06/2020 18:42:56

Have you thought about looking at the connections to the pcb in the reader head. The pcb may have the connections identified.

Martin C

Hi all. I ordered the adapter cable but still no joy. I have decided to buy a unit from m dro and I will buy the relevant scales for the Chinese unit and fit it to my box ford lathe.