Author Topic: MC-050 120 Family - MFOut Pins - OpenLoop vs Closed Loop modes  (Read 193 times)

Offline AR_Plus1_Programmer

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MC-050 120 Family - MFOut Pins - OpenLoop vs Closed Loop modes
« on: January 27, 2020, 03:37:41 PM »
Hello, everyone,

A client of ours is using the MC050-122 model for controlling high torque hydraulics. He needs to manipulate for EDC valves, and we are running into a problem with the output of the pins being current limited.

To help diagnose the problem, we need to know which of the output modes for the MFout pins use open loop mode vs closed loop mode and what the current feedback signal means in those two modes.

The valves require between 300 mA minimum to 700mA maximum each, which is well within the current limits of these MFout pins. For whatever reason, the current is plateauing around 530 mA. We are currently using Output Mode 4 for these pins, and we monitor the feedback current as a fault check.


Offline FluidPowerTom

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Re: MC-050 120 Family - MFOut Pins - OpenLoop vs Closed Loop modes
« Reply #1 on: January 27, 2020, 05:37:16 PM »
Output modes 4 or 5 use closed-loop current control which means that you programmatically tell the microcontroller what current you want that output pin to send, and it will do its best to send that output current even as the coil impedance changes with temperature. 

Mode 3 is duty cycle control wherein you programmatically fell the microcontroller what duty cycle you want that output pin to send, and that effectively just a varying voltage.  This makes no use of current feedback.

My recommendation is to put a checkpoint in your program and verify that you are actually commanding a current above 530 mA.
Mechanical Engineer
Hydra-Power Systems - Distributor - Pacific Northwest

Offline deaks57

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Re: MC-050 120 Family - MFOut Pins - OpenLoop vs Closed Loop modes
« Reply #2 on: January 28, 2020, 12:50:53 AM »
What is the supply volts and load resistance? At 12V, 0.53A suggests a load resistance of 22.6 ohms.