Retrofitting a 1986 Maho MH400E

Thanks for the info Andy. That signals are only created in the HAL is helpful to know. I think my latching problem is in the MAHO relay board. The On button on the MAHO starts the Hydraulics, so I need to physically make that circuit, and see if that enables the latching logic.

While thinking over the latching relay, I decided to wire up the Y encoder and see if I could get progress there.

First thing I found when I started preparing the EXE output cable, is that the wiring colors don't match to MAHO wiring diagram.


According to MAHO, the EXE output cable should have two browns, green red and white. That would have agreed with the modern version of the EXE datasheet


Unfortunatly, the cable is exactly the same as the analog wiring between the scale and EXE per the data sheet. four twisted pairs - White/brown, Green/yellow, Pink/grey, red/blue.

I connected the Y axis encoder, as it is easy to reach and move that motor pulley. White / Brown to (0v / +5V). As long as they are correct, all the other wires such have signals, even if the wrong ones.

This is hm2.5i25.0.0.encoder-01. The HAL for this was generated by the PNCconf. Absolutely nothing can be seen in Linuxcnc or HAL Show. Any troublehooting recommendations would be appreciated.

I already checked that the 7i77 is outputing +5V and 0V on its power pins. I guess my next step will be to put an Osci on the A and B channel pins and see if anything is there. One weird thing is that the EXE circuit board has test points for both 5V and 12V, but in this implementation, 12V is not applied per the MAHO wiring diagram. I can also check that the 5V is correct nthe EXE board.
Mark

For start you can use multimeter, the oscilloscope is better but bulky.
John

drimaropoylos wrote: For start you can use multimeter, the oscilloscope is better but bulky.
John

Not if your oscilloscope is a cheap chinese toy.


I took a quick look at the 19K1 latching today.
I did this test a couple of weeks ago, jumpering between +24V on terminal 200 and terminal 209 and it worked fine...


It is weird, I have 24V output from the 7i84 for this pin, and it is activated correctly by LinuxCNC, into 28x1-2 / OPC1-2 cabe, but the relay is not closing. Checked the resistance between 209 and OPC1-2 and there is no continuaity.


We know that the Phillips standard installation wouldn't latch i if the lube oil system was low, so I am picking that the signal is passed across a couple of other relays on the 28A1 relay board on it's way in from OPC 1-2 to terminal 209. Unfortunately this is not shown on the wiring diagram, so I'd have to search for this somehow. However, to short cut the process, I wired the MESA 7i84 pin directly into the 209 terminal. Still doesn't work. I suspect the the separate 24V rails do not share a common ground.

The batteries then died on my multimeter, so I need to get some more tomorrow.
Mark

A really handy oscilloscope. Any luck with the MahoMH600E configuration Mark?

I pull my cover off the cover off the exe, and it seems I had the correct wiring to 0V and +5V. This voltage is also okay on the EXE test points.

My osci couldn't find any TTL output signals, or any signals at all when I moved the axis though. According to the modern EXE board connector wiring the A/B/Z signals should be on the three pins 4/5/6 (grey/blue/green).

How do I go about measuring the 11µA sine waves coming off the scales? With my multimeter on mA, its lowest scale is 400mA. Do I measure between I1+ to I1- or one pole to ground?

Something I have done has changed the DC power behavior to the relay panel. The panel receives power from all three 24V DC rails, Ignoring the third rail which is only for gearbox shifting, with terminals 201-204 energised immediately, and 201-200 energised once the estop circuit closes.


201 is the common ground between the always on rail to terminal 204, and the second rail to 201. I just measured, and the always on rail drops to 0V, as soon as the E-Stop circuit closes. I can't yet see what I screwed up to create that behavior, but am pretty sure this is causing the non-latching start problem.

**turns out it was a loose connector on the relay board**
Mark

drimaropoylos wrote: A really handy oscilloscope. Any luck with the MahoMH600E configuration Mark?

I am still doing the basic wiring, and trying to get the beast to latch on, and talk with the Heidenhain glass scales. Feels like I have spend hours sitting in front of that control cabinet being very busy achieving nothing.

I haven't reloaded your latest set of config files to see if the classic Ladder file has rungs in it. thanks for the reminder.
Mark