Mesa 7i77 Analog Enable

I'm a new user working my way through commissioning a retrofit of a 3 axis Mill (DeckelFP4NC) with a Mesa 7i92/7i77/7i74 setup, Linuxcnc V2.9.1, Axis GUI. The mill has DC brushed servo motors and I'm using Parker 514C servo drives with an active high enable and -10V to 10V speed setpoint analog input.

I'm not getting any voltage output from the 7i77 ENA signals to enable the servo drive in response to the analogena pin being set high.

Initial setup: 24V to ENA0 , ENA0- to A1 of relay coil, A2- of relay coil to GND. The enable relay didn't turn ON in response to setting hm2_7i92.0.7i77.0.1.analogena high - confirmed in the HAL watch window. I think I may have damaged the 7i77 optocouplers by connecting the ENA- to a relay with a coil current greater than the 50mA specified in the 7i77 manual.

Troubleshooting:
1) I've checked that there's 24V on ENA0 and connected ENA0- to a spare input of the 7i77 (hm2_7i92.0.7i77.0.0.input-31) but don't see this pin change in response to the analog enable.
2) I've shifted the wiring to ENA5 and repeated the test there using the spindle enable pin hoping that the spindle enable might be separated from the other optocouplers - but no response on the input to setting the spindle enable pin high.

Is there anything else I can try before ordering a new 7i77 card?
I've attached an extract from the HAL file used with the analog enable and 7i77 input combination (1).

Thanks in advance for the help - the forum has been a huge help in getting this far. 

While its possible that an optocoupler might have been damaged by driving a relay
with too high a current or no flyback diode, this would have no effect on the other
channels., so I would suspect some other issue, can you set the analog output voltages?

As tommylight said if you are driving a relay, its better to use on of the field output
intended for that task. Is the actual drive enable input a relay coil?

Thanks for suggesting this option of using other outputs but I'd like to keep the safety feature of the drive enable outputs. There may be something else blocking the enable output that I don't understand yet...

Hi PCW - thanks for your reply.
No I haven't been able to set the analog output voltages. Is it possible to determine if the 7i77 is suppressing the ENA out and holding the analog voltages at 0 because of the safety function? I can see the 7i92 watchdog pin which hasn't bit, but I'm assuming that's for comms between the host PC and the 7i92, rather than between the 7i92 and the 7i77?

I'll re-wire the Enable outputs direct to the drives. They are 20mA inputs.

From a testing perspective, having the ENA- connected to a 7i77 input should be OK to tell if the analog enable is working or not?

Is it possible you have watchdog error or sserial error that's masked by the GUI you are using?
Do the digital outputs work?

Yes, digital outputs from the 7i77 appear to be working. I've got a digital output from the 7i77 that turns on the AC aux power to the servo drive via a relay and the servo drive contactor and that is definitely working. 
I'm using the Axis GUI.
How would I check for a watchdog or sserial error? I have an oscilloscope available.

Can you launch LinuxCNC and go to the machine-on state and
then run:

halcmd show all > all.txt

In a terminal and post the all.txt file here?
 

Thanks Tommy - I'll check this out.