With the original plans I´ve started to try to latch on the machine. Seems like a little riddle Maho made up.
The first problem was, that that i wanted to source the 24V+ Logic Power from the machine and not from an extra powersupply. So I´ve searched the source of the intern 24V power line. It comes from The 7K2 and 7K3 line. But you have to energize them with the lighted Button on the Controlpanel, while holding the button you have to latch 19K1 wich is on the relais board and is powered by the 28x1 Pin 2 that is energized by the 7i77. The 7i77 gets it 24V from "Reihenklemme" 202 that is energized from 7K2. It´s a selfholding line.
So...this is the routine:
Hold lighted Button on control (next to emergency stop) -> 24V to the 7i77
Start Linux CNC
set machine enabled (give power to the 28x1 Pin 2 to latch 19K1)
If everything is ok, the 24V line should hold itself now.
Actually that did not work right out of the box, There is K1 in the line that is activated when no emergency stop is pressed and the drives are "ok".
So the machine did not latch at first. I´ve bypassed the K1 and it worked. So my task for tomorrow is to find out why K1 won´t do it´s job.
Onkelmat wrote: But what´s the difference between "NC start" and "NC bereit"?
"NC start" = Output, goes from control panel to enable drives
"NC bereit" = Input, comes from the drives OK signal to the panel or 7i77 or.....
Das ist die unterschied !
I'm not in Maho but generally speaken:
I wan't in any circumstances have my control logic under power. So i can read/see the status of my sensoric always. Specially when something goes not the way i expect.
On the output side it is a bit different. There i want to be able to stop dangerous things surely stopped when estop is pressed. But nevertheless there might be activities that i prefer to have, like signalisation lamps. So generally cupping 24V. I dislike.
On the power side it is a bit trickier, normaly people tent to cut directly from the grid. This can be dangerous for some vfd's when there is mass plus movement. Also most vfd's when switched to max breaking stop faster against mechanical hazzards then going into free run. A typical arguments for estop is electrocution, but in reality I see more the need for fast stop of unwished moving. That's why i prefer a timer that keeps power after estop for a few seconds.
Result of that long sermon is the proposition to sit back and define yourself the wished behaviour of your machine. Than start optimization of your electric. And keep it as simple as possible. Eliminate every part you can.
M5c Mike
I haven't quite followed how you power the mesa card but in general you want to avoid cutting field power to the mesa cards as it can damage the output drivers.
Yes, the 7I77 field power should connect directly to the source, Its ok to break the
connection (say with a fuse or circuit breaker) but it should not be switched on through
a relay or mechanical switch. This is the same with most DC powered devices (step motor
drives etc) because both the power supply and the powered device have bypass capacitors
and very high surge currents can flow between these when switched on instantly.
