Connecting NI-7358 and UMI-7774 to a sinusoidal commutatio​n driver

Question

Hello,
I'm using NI-7358 PCI motion control card and UMI-7774 to drive a brushless servo motor driver Advanced Motion Controls S16A8 External Sine Commutation driver. (It doesn't have isolated ground.)
It's inhibit input like below:
                                ^ 5V
                                 |
                                 >
                                <  10K
                                 |
 (-INH / EN ) o----------------> to control logic
GND              o----------------
                                              |
UMI's inhibit output is connected the drivers inhibit input directly. But there is something wrong with this connection. Control card's inhibit output always stays energized so that driver always stays disabled. (When inhibit input is connected to ground directly it's working properly)
When inhibit signal is active (axis is killed) UMI's inhibit output is 3.5V.
When inhibit is deactived (axis is started) UMI's inhibit output is 4.9V.
NI7358 inhibit is configured active low
UMI 7774 is configured active low
Driver is configured as active low.
I tried both open collector and totem pole configurations of NI7358. Results were the same.
Could you help me please.
Kind regards...
PS: AMC driver's manual: http://www.a-m-c.com/download/datasheet/s16a8.pdf

Answer 1

Hello,
>>1.  What do the lights on the UMI indicate when you change the Inhibit Output Settings in MAX (enabled or disabled)?  When you change these settings make sure you initialize the drive after changes.
inhibit disabled from MAX ------>   UMI Disable led is always on
inhibit enabled from MAX ------->   UMI Disable led is on when axis is killed
                                                 UMI Disable led is off when axis is started
>>2.  If you have the drive inhibit line connected directly from the UMI to the drive what are the results of changing these inhibit output settings?  Are there any LEDs on the drive to indicate if it is enabled or not?
When the inhibit line is connected to drive directly, it's enable led is always red (it means disable) since it configured as active low. When I change its polarity to active high it always indicates green (enabled) whether the UMI's inhibit line is low or high.
When inhibit signal is active (axis is killed) UMI's inhibit output is 3.5V.  When inhibit is deactived (axis is started) UMI's inhibit output is 4.9V.
>>3.  What happens if you reverse the polarity in MAX and/or the UMI?
Drive is always green or red according to drive's inhibit polarity.