Mesa 7i96 power up state

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28 Mar 2020 14:12 #161812 by GND
Mesa 7i96 power up state was created by GND
I just wanted to be absolutely sure of the power up state of a Mesa 7i96 before I jump in and attach it to real motors!

The only mention I could find in the Mesa manual was a description of the state of the expansion connector I/O - though it's quite possible I could have missed what I was looking for.

However from searching the forum, my assumption is that all the general purpose output switches will be guaranteed to be OFF - until the point that LinuxCNC is safely in control. Since the Step & Dir outputs are buffered, I am similarly assuming that these will be held safely INACTIVE (according to their polarity), again until LinuxCNC is in charge. If this is all true, then I should be able to safely power my system before running LinuxCNC, and nothing untoward will happen!

Any words of confirmation on my assumptions - or putting me straight - would be appreciated!

All the best
Graeme

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28 Mar 2020 14:21 #161815 by tommylight
Replied by tommylight on topic Mesa 7i96 power up state
I have done several retrofits of big industial machines with Mesa boards, all of them are fully powered as soon as the main switch is turned on and nothing will move untill Linuxcnc is loaded and F1 and F2 active in Linuxcnc.
That assumes the wiring is properly done by disabling the power where needed untill F1 is active, and disabling the drives untill F2 is active.
Those are of utmost importance for having a safe machine.

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28 Mar 2020 14:32 #161816 by PCW
Replied by PCW on topic Mesa 7i96 power up state
7I96 isolated outputs are in the off state at power up but a safe design
should always have ESTOP hardware that can disable the axis drives and
spindle/torch independent of any software settings

The step /dir outputs on a 7I96 may toggle once at start-up so you should not depend
on then being inactive, though they will not generate a pulse stream at start-up
and a watchdog timeout will stop any pulse stream if the 7I96 losses communication
with the host computer.

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28 Mar 2020 14:46 #161817 by GND
Replied by GND on topic Mesa 7i96 power up state
Thanks for the quick responses guys. I'm retrofitting an existing commercially made CNC mill which has all the ESTOP wiring in place, though I have yet to unravel it and understand exactly how it is set up. At this initial bring-up stage, I just wanted to be sure that the Mesa card wasn't going to be uncontrolled or in an unknown state before the software was ready. I guess I knew it wouldn't be - but just wanted to be 100% sure!

So I assume machine builders typically generate their own physical signal outputs to sequence power up and enables to the various parts of their machines? Based on the state of F1, F2 and other things like the ESTOP switches? Coming from Mach3, I don't think that was an available option, but sounds like the right way to go.

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