Can't change decel on the fly on HDC2450

6 years 7 months ago #29528934 by lemma.r
I have setup default accels and decels for two open loop controlled motors attached to a HDC2450. These values are being honoured and are working fine.

For ESTOP use we have a safety relay dropping the main contactor after a 0.5second delay. There is an instant output from the safety relay going to the HDC2450 that we want to use to trigger a rapid controlled deceleration to stop before the main contactor drops out.

Our motor has MaxRPM set to 1000. So a value of 20000 should give us the correct decel in tenths of seconds for a 0.5 second ramp to stop.

In my microbasic script I am monitoring the Estop input and attempting to set a short decel time if estop is hit. When estop is released I restore the default decel time for the axis. I have had no success in microbasic with changing the decel on the fly. I've tried a large range of numbers and it always seems to decel in the default time for the axis. I am trying:
SetCommand(_DECEL,1,20000) 'rapid stop both motors
SetCommand(_DECEL,2,20000)

To then stop the motors I have tried 3 different methods to see if any of them would do what we are looking for:
'first attempt
SetCommand(_ESTOP,1)

'second attempt
SetCommand(_MSTOP,1)
SetCommand(_MSTOP,2)

'third attempt
SetCommand(_GO,1,0)
SetCommand(_GO,2,0)

I've also tried the !DC 1 20000 command from the Console tab while the motor is moving and that doesn't seem to make any difference either.

Any suggestions as to how to change decel on the fly?

Motor Control Utility Rev 1.2 1/4/14, HDC2450 firmware v1.2 RCB400 10/10/2013

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6 years 7 months ago - 6 years 7 months ago #29528939 by Griffin Baker
Replied by Griffin Baker on topic Can't change decel on the fly on HDC2450
setcommand(_EX, 1) to latch estop
setcommand(_MG, 1) to unlatch estop

If you are in open loop, try changing the max speed to a lower value like 100 and the decel to a higher number like 50000.

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6 years 7 months ago #29528941 by lemma.r
Thanks, I'll give that a go (we are using open loop). Does the _ESTOP command honour the current decel ramp set for an axis? Or does it use the default decel? Or some other value?

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6 years 7 months ago #29528942 by Griffin Baker
Replied by Griffin Baker on topic Can't change decel on the fly on HDC2450
No. The estop basically shuts off the fets. So what you wind up with is a coasting to a stop. Therefore no regenerative braking will ever be applied.

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6 years 7 months ago #29528943 by lemma.r
Thanks, I'll avoid _ESTOP then as I require a controlled stop.

What about _MSTOP? Does it use the current decel? Or default decel? Something else?

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6 years 7 months ago #29528945 by Griffin Baker
Replied by Griffin Baker on topic Can't change decel on the fly on HDC2450
From running this in the console it appears to do so. I used the !MS 1.

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