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ICSHWI-14996: Use EL7047 brake control for grids

Carlos Neto requested to merge grid-el7047-brakes into main

We want to use EL7047 internal brake control (terminal 8).
Problem is currently both terminals 4 (other grid) and 8 (respective slit) are being used for STO/interlock.

This means 3 things:

  1. We had to rewire the collision avoidance system to provide a single wire carrying the logical AND between both signals (i.e.: other grid status AND respective slit status) to be connected into terminal 4.

This was implemented by connecting both signals in series (limit switch comes first) to avoid relays.
See example below:

For grid #1

24V --> grid #2 N.O. --> if switch is NOT pressed signal ends here
24V --> grid #2 N.O. --> if switch IS pressed --> sends 24V to slit 1 N.C. --> if slit 1 IS retracted signal ends here
24V --> grid #2 N.O. --> if switch IS pressed --> sends 24V to slit 1 N.C. --> if slit 1 is NOT retracted --> signal arrives at grid 1 EL7047 terminal 4

This frees up terminal 8 but at a price: we can no longer distinguish the cause of a NOK signal
i.e.: we don't know if the other grid is inserted or if our slit is extracted, we only know it is NOK.

So there is no point in having safetomove.plc (and consequently safetommove.db) for the grids anymore.

  1. Since break control is handled by EL7047 fw/mc we don't have access to brake status anymore.
    I am currently investigating if we can still keep/get this information from the module.
    If it is possible, it will be re-added in a future commit.

  2. With all of this done we do not require controllable outputs anymore (no need for EL2808).
    So both EL1018 and both EL2808 were replaced by a single EL1808 which has enough inputs and at the same time provides constant 24V for the switches and collision avoidance wiring.

Please also note that all of these changes are planned for the slits as well, and will be done in a future MR.

Edited by Carlos Neto

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