Overload. What does it mean?

Luke Ricker 8 years ago updated by Gustav Widén (System support) 8 years ago 2

From time to time on various pieces of our MDL2 equipped machines, we'll get get an "Overload" error on a COUT channel.

The COUT channel connects directly to a 350-650 mA valve solenoid that runs an engine cooling fan.

What exactly does "overload" mean in this context? If a COUT channel is basically a PWM output with current monitoring, how can the controller ever overload the output?

What are the specifics that the controller looks for to register an overload error on a COUT?



The COUT overload is triggered when the measured current is above the commanded current, and the COUT current regulation cannot reduce it anymore.

This switches off the COUT on both the COUT and CRET pins, and it is necessary to first give a zero command before it can attempt to activate again.

Shorting the CRET to ground would have this effect, but there are other possibilities.

An actual overload of the high-side driver, like shorting the COUT pin to ground may give this dialog, but that fault may actually show up as an open load instead, as the highside driver itself will switch off also.

Trying to command a current below the specified 100 mA limit can trigger either open or overload, as an effect of the regulator becoming unstable.