Port 1. Isolated Output issue

[MarkoTr]

Hello everyone, I have a problem with port 1. isolated output on AXBB.
My system contains:
1) Delta vfd
2) SHCRACK relay 24VDC
3) MV power supply 24v-36W-1.4A
4) AXBB
5) Spindle 220V 3KW (only use M3)

I connect: Delta-AXBB (AVI/AO1 ACM/5V0)
Relay-AXBB-PowerSupply (A1/Port 1. Isolated Output O3 A2/24V)
DeltaVFD-Relay (MDI/NO14 DCM/COM11)

Spindle speed control (0-10V) works perfectly. But from some reason, when I try to turn on the MACH 3 software at maximum speed, everything works normally, and when I measure the voltage on the incoming relay signals (A1 and A2), I have 24V. As I try to reduce the speed of the spindle, the voltage at the input (A1 and A2) starts to drop, and it increases at the isolated output O3, and my spindle shuts down. It's not clear to me why this happens since I don't use any other outouts, they are all disabled by software when they are NPN type.

Everyone's opinion would mean a lot to me. Thanks in advance.

[cncdrive]

Please post your MAch3 xml file which contains your settings.
And also let me know on which exact output is the relay is on now and maybe it would be also helpful if you could post a g-code file which which the issue is reproducable and then we will test and debug the problem here.