[SOLVED] 7i76ED - overcurrent/overtemp error

I'm getting intermittent overcurrent and/or overtemp errors when I trigger my air solenoid relays.  Relays are 24vdc coils and have built-in flyback diodes.

Relay coils are well inside the published current limits for the 7i76ed.  Field voltage is right at 24v.

Using these: www.automationdirect.com/adc/shopping/ca..._(rs_series)/rs4n-de


EDIT - errors happen when I de-energize the relays, not when they're turned on.


Any idea what's causing this?
 

What is the total current draw of all solenoids?
There is a max current limit per driver chip in addition to the per output current

Also, if you are using the relays to drive the solenoids, do the solenoids have suppressor diodes?

The relays each draw 8ma, one per 7i76 output.
Solenoids each draw 125ma.

The ones I've been having problems with are outputs 02, 03, and 10.  #10 is my ATC door, #2 is ATC extend, #3 is ATC retract.

The solenoids themselves don't have diodes... that's one of the reasons I used relays with built-in diodes.

Both the relay coils and solenoids 24vdc-in are connected to the same terminal block, through a fuse and contactor.  Solenoid 0vdc is connected to my 0vdc rail.

7i76 field power is fed from the same power supply, through a fuse and no contactor.  7i76 field 0vdc is connected to 0vdc rail.

Could the solenoid field collapsing be back-feeding through the terminal block to the 7i76 outputs?

Do I need to add diodes to all my solenoids now?

Yes, you can generate enormous amounts of EMI when breaking
DC current to inductive loads with contacts. This will also eat your
relay contacts...

So a diode across the +/- of the solenoid connector should do the trick?  I've got a handful of 1N4148's left over from a keyboard build.

Yes a diode across the coil, cathode to +

Thanks, that seems to have done the trick.