Mesa 7i77 remote error = (27) over current
31 Jul 2024 07:34 #306467
by pietxs
Mesa 7i77 remote error = (27) over current was created by pietxs
Hello, I have the following problem with my 7i77 card.
I take the card's field voltage from my Maho machine, it's around 29V. I connected the machine's original relays to the outputs. Unfortunately I get the following error: hm2/hm2_7i77.0: Smart serial card hm2/hm2_7i777,0.7i77.0.0 remote error = (27) Over Current
I have already removed all outputs and inputs, unfortunately the error still persists. I completely disconnected the power supply and switched off the PC. Unfortunately the same error always occurs when restarting and output 08-11 is permanently "on".
Can I reset the card somehow? Can I fix the error by rewriting the firmware?
Surely the outputs should be able to withstand the switching loads of the relays?
I hope someone has a helpful idea for me
I take the card's field voltage from my Maho machine, it's around 29V. I connected the machine's original relays to the outputs. Unfortunately I get the following error: hm2/hm2_7i77.0: Smart serial card hm2/hm2_7i777,0.7i77.0.0 remote error = (27) Over Current
I have already removed all outputs and inputs, unfortunately the error still persists. I completely disconnected the power supply and switched off the PC. Unfortunately the same error always occurs when restarting and output 08-11 is permanently "on".
Can I reset the card somehow? Can I fix the error by rewriting the firmware?
Surely the outputs should be able to withstand the switching loads of the relays?
I hope someone has a helpful idea for me
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31 Jul 2024 14:10 #306524
by PCW
Replied by PCW on topic Mesa 7i77 remote error = (27) over current
A stuck output means a damaged driver chip.
Driver chips can be damaged by:
1. Excessive supply voltage (can the field voltage surge above 32V?)
2. Inductive loads > ~60 ma if they do no have a flyback diode
(flyback diodes are recommended in all cases)
The chip can be replaced by returning the 7I77 to Mesa
Driver chips can be damaged by:
1. Excessive supply voltage (can the field voltage surge above 32V?)
2. Inductive loads > ~60 ma if they do no have a flyback diode
(flyback diodes are recommended in all cases)
The chip can be replaced by returning the 7I77 to Mesa
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01 Aug 2024 02:28 #306577
by Benb
Replied by Benb on topic Mesa 7i77 remote error = (27) over current
The 7i77 card outputs use NCV7806 IC. These chips are sensitive to overvoltage and overcurrent. You can reduce the chances of frying them by NOT disconnecting the 24vdc supply side of the card to avoid overvoltage. Use slave relay cards to avoid overcurrent.Have look at the attached picture. Centroidcnc equip their low-cost CNC cards with hobby grade relay card and hard wire the dc supply side (I would solder the wires) to further reduce headaches with fried chips and provide an AC plug for power disconnections.Centroidcnc has been in the business of dealing with hobbits for long time, they know how to reduce issuance of RMA’s (PCW knows what I am taking about).
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01 Aug 2024 03:04 - 01 Aug 2024 03:04 #306578
by PCW
Replied by PCW on topic Mesa 7i77 remote error = (27) over current
The NCV7608s are quite fine with inductive loads up to their rated 350 mA,
but larger inductive loads must have a flyback diode. The NCV7608s can
also be damaged by excessive field voltage or switching the field voltage with
a mechanical switch or relay contact.
Also 29V is odd for relays and suggests an unregulated supply, which may also
be an issue.
but larger inductive loads must have a flyback diode. The NCV7608s can
also be damaged by excessive field voltage or switching the field voltage with
a mechanical switch or relay contact.
Also 29V is odd for relays and suggests an unregulated supply, which may also
be an issue.
Last edit: 01 Aug 2024 03:04 by PCW.
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