Control a VFD with a Micrologix 1100

[barthautala 1]

The VFD is an ABB ACS550. It has a few pre-programmed macros in its system now. Looking through the manual I think Id like to use the macro "Alternate". Here is what I want to do. I want to set up a test bench to motor. I want to have the ability to control the motor either manually with a POT or automatically with a PLC program. Im thinking that the input AI1 on the VFD is what I want to hook to. Can anyone confirm this? Also, what would the ladder look like for this portion? I have an idea but again, Id like to confirm. I was thinking of hooking the POT to the analog input on the PLC and using 2 seperate outputs - one in a manual subroutine and one in an auto subroutine to discern which output should be sent to the VFD. Im a long time listener and first time caller to this website.

[PLCMentor.com 60]

Hi and welcome to the forum! I think you will be amazed at the people that visit and the advice offered. I need to make a quick post so let me just hit your last statment on the AO's. You really dont need 2 analog outs just one. You can use logic to decide whether to copy the result from automatic or the manual logic to the output. So if you have the system in manual the manual speed setpoint will be sent to the output. If the system is in auto the result of the automatice speed logic will be sent as a speed setpoint to the output. Russell

[barthautala 1]

HA - thanks. Copy. Yeah I knew that I was testing you. BTW, your website is great. I used it quite abit in refreshing myself. My background is mechanical but Ive done a couple of things with a PLC - mostly simple discreet stuff. One project with an LVDT. Motor controlling is new to me. Edited 8 Apr 2009 by barthautala