How to Enable an A.C.drive using PCI7344 motion controller

[Giridhar_Rajan]

Hi,

I have an A.C. Servo Drive. The drive enable bit in the drive takes 24V DC. I'm using NI  PCI7344 motion controller with extension UMI7764 board. How to enable/disable the AC Servo drive. Which pin in the motion controller should I connect to the drive to enable disable it. Also, there is a VI provided in LabVIEW to configure drive. What does that VI do.

Regards,

Giridhar Rajan

Automation Engineer

Cruiser Controls

Mumbai, India

[Buechsenschuetz]

You can connect the INH (inhibit) output of the PCI7344 to the enable/disable input of your drive. However, the PCI7344 will deliver a TTL signal (2.8V) only. You cannot connect a 24V line directly to the output, it will destroy the card.

You will need some kind of high voltage driver interface. You can use open collector drivers such as an ULN2803, and you also need a 24VDC circuit (check whether the drive can supply 24VDC). However, to avoid any occasional damage of the board due to short circuits etc I would recommend using a solid state relay such as AQV212 by Matsushita.

In most cases activating the disable input will cut off power to the motor, i.e. the shaft will rotate loosely. Since this is an unwanted condition in many cases (imagine a lift or a crane) in most cases the disable inputs of drivers are NOT software controlled at all and wired to a fixed voltage level

[Jochen]

Another option would be to upgrade the UMI-7764 to an UMI-7774 which provides isolated 24 V connectivity for inhibit signals, global stop inputs, triggers, limits, home and digital I/O.
If this sounds interesting to you please contact your local NI office and ask for a hardware upgrade to the UMI-7774.

Best regards,

Jochen Klier
National Instruments Germany

Message Edited by Jochen on 08-24-2005 02:26 PM

[Giridhar_Rajan]

Hi,

Thanks Jochen and Buechsenschuetz. Your suggestions were very helpful.

Regards,

Giridhar Rajan

Automation Engineer

Cruiser Controls

Mumbai, India