Motor chattering when contactor off

2 years 8 months ago #29533466 by rfrancis
I'm using a (now obsolete) LDC1430 to power a winch motor from a nominal 12V battery. I am using a contactor to isolate the 2 Vmot lines as recommended. I am switching Pwr-Ctrl to battery 0V to disable the controller, and battery +12V to keep the controller alive if the contactor is off.

I am running in closed-loop position mode. Usually there is a residual loop error of 2 or 3 encoder counts when the system comes to rest. I have been unable to reduce this to zero.

If, when the system has stopped, I open the contactor, the motor chatters. Here is a zipped recording made with my iPhone -- it's a bit quiet, but you can hear the click as I switch the contator off, then the chattering, then the click as I switch it back on.

File Attachment:

File Name: Chattering.m4a.zip
File Size:72 KB


All inputs have been disconnected except the RS232, which is going through a 3-line opto-isolator.

The encoder itself is powered by the +5V on the D-SUB connector, and is connected to the D-SUB ground too. There is no connection here to the battery 0V.

Do you have any idea how to eliminate this annoying chatter?

cheers,
Richard
Attachments:

Please Log in or Create an account to join the conversation.

2 years 8 months ago #29533468 by Gabriel_Isko
Replied by Gabriel_Isko on topic Motor chattering when contactor off
Hello Richard,

Is the motor throwing an UnderVolt fault when you shut off power to VMot?

Please Log in or Create an account to join the conversation.

2 years 8 months ago #29533472 by rfrancis
Hi Gabriel,
yes, it is showing undervoltage. I get it in the reported flags as well as in the flashing light pattern (though that is irregular). The voltage reported is between 4 and 5 volts (not constant).

cheers,
Richard

Please Log in or Create an account to join the conversation.

2 years 8 months ago #29533475 by Gabriel_Isko
Replied by Gabriel_Isko on topic Motor chattering when contactor off
If it has an undervoltage fault, it should be shutting off power to the output stage. It seems like voltage is still leaking out though. This could be a bug in the firmware or a hardware problem, but since we no longer support the LDC1430 there is nothing I can recommend for a fix.

Please Log in or Create an account to join the conversation.

2 years 8 months ago #29533476 by rfrancis
Hi Gabriel,

Thanks for your diagnosis that it may be either a firmware or hardware problem (ie, RoboteQ's fault).

I am less impressed by your statement that since this device is no longer on sale, RoboteQ is not able to offer any support to fix the problem. Particularly since it seems that changes in your product portfolio in this area are largely cosmetic.

Cleary this is counter-productive. It gives the clear message that it's not a good idea to purchase any of your controllers because the moment the controller is declared obsolete (which the buyer has no control over) the support disappears.

If I choose to buy any of your controllers today, you might declare it obsolete tomorrow, and support vanishes.

Frankly, I'm disappointed. I have now invested in three generations of your controllers, and even though the latest of them is only 4 years old (and was a new product when I bought it), you can't support it.

I have spent all of of my career n the aerospace business, and in my experience any company which refuses support for recent products like this will not survive. Buyers quickly learn.

Please Log in or Create an account to join the conversation.

2 years 8 months ago #29533480 by blake
Hello Richard,

The LDC1460 was discontinued in 2014 after a standard EOL term and replaced by a comparable part (MDC1460). Firmware maintenance continued for the LDC1460 through March of 2015. I have records here that I sent you the latest updated version of LDC1460 firmware on March 14th of last year, I assume this is the version you are using now. If not I can resend.

I understand your concern but unfortunately the LDC1460 is obsolete and has been for over 3 years. We would be happy to replace the LDC1460 for you with the modern replacement (MDC1460) under our Extended Warranty Program. If you would like to do this please feel free to contact me at This email address is being protected from spambots. You need JavaScript enabled to view it..

Thank you,
Blake

Please Log in or Create an account to join the conversation.

Moderators: tonysantoni
Time to create page: 0.830 seconds