Intermittent overload COUT error

SJ L 2 years ago in Master modules / MC4x updated by Gustav Widén (System support) 9 months ago 8

Hi, I have an issue with intermittent MC43 COUT overload errors on one of our machines.

Status is OK and operates well in most conditions, but will randomly report overload (even when that function is not requested).

I have tested the solenoids, plugs, and wiring harnesses within this circuit and all looks ok.

COUT circuit C1:16, 41, 57.

Is there anything else I should check to see what might be going wrong?

For MC43 COUT-C (C1:16, 41, 57), also check the adjacent MC43 COUT-D (C1:30, 42, 58)

When an overload is detected on either of the two COUTs, the shared supply to the two adjacent channels is cut, and both get the status overload. 

Another point to check is the COUT min current. If you try to control a current too far below the specified 100 mA, the regulator could have problems. This will also affect both channels, even if one is inactive. 

Thank you for that, I wasn't aware the two COUTs shared supply. 

From that, I terminated the connections on the COUT-D circuit - they were previously optional outputs that were not being used on this machine. 

However, the issue still remains where COUT-C is getting the overload error, intermittently. 

The minimum requested current for the channel is 350mA.

Are there any other checks I could complete?

The next thing to check could be the load; if you have a large load (low resistance), the problem could be that the peak current could becomes too high. 

For example, if powering a 12 V coil in a 24 V system. 

See Maximum load in the MC4x Appendix A info: 

Image 3397

If this is the case, setting a higher dither frequency on the COUT could help. 

You find the COUT PWM frequency on the MC4x module pin properties in IQANdesign. 

Hi, I increased the PWM frequency but this still hasn't addressed the issue. 

The OVERLOAD error shows, intermittently, even when no output has been request for that COUT function. 

I am working on some logic to mask this as best I can but still need to find the root cause.

Hi, could I draw attention to this again please? We are having another MC43 unit that is showing the same issues as mentioned above. 

The above situation was awkwardly resolved by using an XC41 controller and putting the output on it instead - which obviously isn't an ideal solution, one I would like to avoid again. 

The COUT channel status intermittently changes from OK to OVERLOAD. 

We have not changed the proportional solenoid valve that this output controls, and there are 2 others in the system on the other output lines that are working ok. 

What else could be the cause of this?

As you say it happens when the output is off, I recommend looking for shorts in the wiring. 

IQAN MC4x/XC4x instruction book Appendix B has a list with COUT statuses for different errors. When the COUT is off, the overload status can be caused by highside short to ground or lowside short to ground. 

As the status changes intermittently, it could be that bending and flexing of the wiring harness might have an impact.

What you describe is the exact issue we are having but with different pins. We are using a COUT single direction on C2:67 and C2:15, and an optional bidirection COUT C2:68/C2:16/C2:32. On the optional side, we don't have it connected as the option has not been ordered. We are constantly getting an overload on the C267/15 output even when the option output function group is turned off. This is on multiple machines now, we have checked coil, wiring, output, connectors and no resolve. What we have noticed that might help we are testing now is to remove the option COUT all together. Can you give insight on why this might be?

COUT-J (highisde on pin C2:68) is the adjacent channel to COUT-I (highside on pin C2:67).

Image 3890

If there is a short to ground on one of the COUTs, the reaction is to switch off the shared highside and report overload on both channels. 

This can cause some confusion if it is the disabled COUT that is shorted to ground. Having the channel disabled hides the error message for that channel, but the diagnostic function is still running. Only the enabled channel will show the overload error message.