ABB VFD connection to Analog output card

dear,

i want to connect an analog input card to VFD terminal.
my understanding is that it can be connected to AI1+ and AI1- as indicated in the attached diagram. I could not understand the symbol used in the attached showing connection between AI1+, AI1- AGND going to a box

thanks for clarifying

They are not quite going to a "box"...
AI1+ is connected to the "wiper" of a potentiometer which's full voltage reference is supplied by the +VREF and -VREF terminals.
This is an example of "Voltage Analog Input" setup (determined by the AI1 hardware jumper); this type of setup also requires the AI1- terminal to be connected to the AGND one.
Varying the resistance of the connected potentiometer will vary the voltage between the AI1+ and AI1- terminals.

Dear dmargineau,

Thank you for the clarification. So i assume that i can connect analog card output to AI1+ and AI1- without any problem.

Well, not quite so...
You will need to use an Isolated Analog Output type card and after choosing the interface output point, you will have to connect the VFD's terminals +VREF and -VREF to the respective output "full reference" terminals while the "active/variable" channel terminal will be connected to the AI1+.
To make a long story a lot shorter, you will have to use the ACS850's internal DC voltage power supply as the full reference of the isolated analog output channel to be used as reference means by the VFD.