Testing homing limits resulted in motor stall errors with Mach1 #APCC


Leo Shatz
 
Edited

Hello,

Recently I had a very productive remote session with Howard Hedlund from A-P, who helped me to setup meridian and homing limits. I did some tests following the session and I've got some issues I'd like to raise here:

Meridian flips were fine, I didn't run in any problems with flips going the wrong way, as long as the red telrad circle was staying within meridian limits. However, I had motor stall event triggered a couple of times in the following situations:
 
- I've defined an action of "stop tracking and slewing and park in place" in homing limits and let the mount perform unsafe pier flip. When it hit the homing limit (well before colliding with the pier), the mount stopped, the message saying that limit was reached and dialog box flushing. Few moments after that, since SGP was configured to perform parking on its own, it tried to perform parking but failed as mount was already parked. I've seen a yellow flashing sign in APCC indicating an error and there was freshly triggered "motor stall" event.
 
- I did the slow slew (at rate x200) to move CWs up higher until it reached the homing limits, the mount stopped again with a message from APCC and there was another motor stall event.

After both cases I was able to unpark the mount and perform slewing in both axis (without manually turning power off/on to the mount).
 
I'm afraid to repeat these tests as there could be potential problems with the hardware, although it looks to me more like a software glitch under these circumstances. I hope it's not actually caused by a physical issue with the mount, but possibly a software issue where there is some race condition in detecting abrupt change in motor speed and control signal stopping the slewing/tracking at horizon limit.

Leo Shatz
 


Leo Shatz
 
Edited

I'm using APCC Pro version 1.8.3.1 and VCP4-P01-13 firmware.


Dale Ghent
 

So, the primary cause of a motor stall is an external mechanical force that is countering the direction that the motors are driving the axes in question. Sometimes it's electrical, such as your power source (such as a battery) furnishing too little voltage to the mount.

Since you didn't mention verifying the physical condition of the mount and the stuff you have hanging off of it, have you checked balance of both RA and dec and looked for any cable wrapping or snags that could be catching and preventing one of the axes from turning past a certain point?

You assertion that the issue might be software-based is misinformed - APCC and the ASCOM driver sends commands to the mount controller to slew and move to the requested point; so the software on your computer is not responsible for actually driving the motors themselves every micrometer of the way. It's impossible for APCC to be directly responsible or the cause of a motor stall.

Describe your mount's load in more details and the work you have done to verify balance, as well as any other mechanical configuration issues that would be the most likely causes of a stall event.

/dale

On Jul 31, 2020, at 7:22 AM, Leo Shatz <leonid.shatz@gmail.com> wrote:

Hello,

Recently I had a very good remote session with Howard Hedlund from A-P, who helped me to setup meridian and homing limits. I did some tests following the session and I've got some issues I'd like to raise here:

Meridian flips were fine, I didn't run in any problems with flips going the wrong way, as long as the red telrad circle was staying within meridian limits. However, I had motor stall event triggered a couple of times in the following situations:

- I've defined an action of "stop tracking and slewing and park in place" in homing limits and let the mount perform unsafe pier flip. When it hit the homing limit (well before colliding with the pier), the mount stopped, the message saying that limit was reached and dialog box flushing. Few moments after that, since SGP was configured to perform parking on its own, it tried to perform parking but failed as mount was already parked. I've seen a yellow flashing sign in APCC indicating an error and there was freshly triggered "motor stall" event.

- I did the slow slew (at rate x200) to move CWs up higher until it reached the homing limits, the mount stopped again with a message from APCC and there was another motor stall event.

After both cases I was able to unpark the mount and perform slewing in both axis (without manually turning power off/on to the mount).

I'm afraid to repeat these tests as there could be potential problems with the hardware, although it looks to me more like a software glitch under these circumstances. I hope it's not actually caused by a physical issue with the mount, but possibly a software issue where there is some race condition in detecting abrupt change in motor speed and control signal stopping the slewing/tracking at horizon limit.

Leo Shatz


Roland Christen
 


'm afraid to repeat these tests as there could be potential problems with the hardware,
The "Motor Stall" warning will occur when unsafe limits are exceeded. This is not a warning that something is wrong with the motor or electronics, it is simply telling you that the software has turned off the power to the motors to prevent your scope from being damaged. At this time we use the same error code for all situations where the motor power has been turned off. It probably could be changed to indicate not "motor stall" but "motor power deactivated".  However, we have many other software challenges right now and this one will have to wait a bit. Be assured that nothing bad has happened to your electronics or the motors.

Rolando


-----Original Message-----
From: Leo Shatz <leonid.shatz@...>
To: main@ap-gto.groups.io
Sent: Fri, Jul 31, 2020 6:22 am
Subject: [ap-gto] Testing homing limits resulted in motor stall errors with Mach1 #APCC

Hello,

Recently I had a very good remote session with Howard Hedlund from A-P, who helped me to setup meridian and homing limits. I did some tests following the session and I've got some issues I'd like to raise here:

Meridian flips were fine, I didn't run in any problems with flips going the wrong way, as long as the red telrad circle was staying within meridian limits. However, I had motor stall event triggered a couple of times in the following situations:
 
- I've defined an action of "stop tracking and slewing and park in place" in homing limits and let the mount perform unsafe pier flip. When it hit the homing limit (well before colliding with the pier), the mount stopped, the message saying that limit was reached and dialog box flushing. Few moments after that, since SGP was configured to perform parking on its own, it tried to perform parking but failed as mount was already parked. I've seen a yellow flashing sign in APCC indicating an error and there was freshly triggered "motor stall" event.
 
- I did the slow slew (at rate x200) to move CWs up higher until it reached the homing limits, the mount stopped again with a message from APCC and there was another motor stall event.

After both cases I was able to unpark the mount and perform slewing in both axis (without manually turning power off/on to the mount).
 
I'm afraid to repeat these tests as there could be potential problems with the hardware, although it looks to me more like a software glitch under these circumstances. I hope it's not actually caused by a physical issue with the mount, but possibly a software issue where there is some race condition in detecting abrupt change in motor speed and control signal stopping the slewing/tracking at horizon limit.

Leo Shatz
 


Leo Shatz
 

Dale,

I've mentioned it in description of the problem that there was no external mechanical force on the mount - it stopped at homing limit as was set in APCC.
The mount was well balanced in both Ra and Dec.
There was no payload, no telescope mounted on top, just scope rings with losmandy plate and a smallest CW just to balance everything (when freeing the Ra/Dec locks each axis was almost perfectly balanced).
This was done for testing purposes alone.

I still wonder why motor stall events were triggered at a moment when mount was parked in place when hitting homing limit (and I repeat - it didn't hit anything physically at that moment).

Thanks,

Leo


Roland Christen
 


I still wonder why motor stall events were triggered at a moment
I explained that in a previous e-mail. Did it not come thru?

Rolando


-----Original Message-----
From: Leo Shatz <leonid.shatz@...>
To: main@ap-gto.groups.io
Sent: Fri, Jul 31, 2020 10:02 am
Subject: Re: [ap-gto] Testing homing limits resulted in motor stall errors with Mach1 #APCC

Dale,

I've mentioned it in description of the problem that there was no external mechanical force on the mount - it stopped at homing limit as was set in APCC.
The mount was well balanced in both Ra and Dec.
There was no payload, no telescope mounted on top, just scope rings with losmandy plate and a smallest CW just to balance everything (when freeing the Ra/Dec locks each axis was almost perfectly balanced).
This was done for testing purposes alone.

I still wonder why motor stall events were triggered at a moment when mount was parked in place when hitting homing limit (and I repeat - it didn't hit anything physically at that moment).

Thanks,

Leo


Leo Shatz
 

Rolando,

Thank you for answering my concerns. Your explanation makes sense to me now.

Leo


Christopher Erickson
 

Having a low voltage halt result in a solid yellow light and a limits halt result in a blinking yellow light and a hardware stall resulting in a S.O.S. blinking light (for examples) would be a nice feature to eventually add to the CP4 firmware.


On Fri, Jul 31, 2020 at 5:01 AM uncarollo2 <chris1011@...> via groups.io <chris1011=aol.com@groups.io> wrote:

'm afraid to repeat these tests as there could be potential problems with the hardware,
The "Motor Stall" warning will occur when unsafe limits are exceeded. This is not a warning that something is wrong with the motor or electronics, it is simply telling you that the software has turned off the power to the motors to prevent your scope from being damaged. At this time we use the same error code for all situations where the motor power has been turned off. It probably could be changed to indicate not "motor stall" but "motor power deactivated".  However, we have many other software challenges right now and this one will have to wait a bit. Be assured that nothing bad has happened to your electronics or the motors.

Rolando


-----Original Message-----
From: Leo Shatz <leonid.shatz@...>
To: main@ap-gto.groups.io
Sent: Fri, Jul 31, 2020 6:22 am
Subject: [ap-gto] Testing homing limits resulted in motor stall errors with Mach1 #APCC

Hello,

Recently I had a very good remote session with Howard Hedlund from A-P, who helped me to setup meridian and homing limits. I did some tests following the session and I've got some issues I'd like to raise here:

Meridian flips were fine, I didn't run in any problems with flips going the wrong way, as long as the red telrad circle was staying within meridian limits. However, I had motor stall event triggered a couple of times in the following situations:
 
- I've defined an action of "stop tracking and slewing and park in place" in homing limits and let the mount perform unsafe pier flip. When it hit the homing limit (well before colliding with the pier), the mount stopped, the message saying that limit was reached and dialog box flushing. Few moments after that, since SGP was configured to perform parking on its own, it tried to perform parking but failed as mount was already parked. I've seen a yellow flashing sign in APCC indicating an error and there was freshly triggered "motor stall" event.
 
- I did the slow slew (at rate x200) to move CWs up higher until it reached the homing limits, the mount stopped again with a message from APCC and there was another motor stall event.

After both cases I was able to unpark the mount and perform slewing in both axis (without manually turning power off/on to the mount).
 
I'm afraid to repeat these tests as there could be potential problems with the hardware, although it looks to me more like a software glitch under these circumstances. I hope it's not actually caused by a physical issue with the mount, but possibly a software issue where there is some race condition in detecting abrupt change in motor speed and control signal stopping the slewing/tracking at horizon limit.

Leo Shatz
 


Roland Christen
 

Ok.

Rolando



-----Original Message-----
From: Christopher Erickson <christopher.k.erickson@...>
To: main@ap-gto.groups.io
Sent: Fri, Jul 31, 2020 12:31 pm
Subject: Re: [ap-gto] Testing homing limits resulted in motor stall errors with Mach1 #APCC

Having a low voltage halt result in a solid yellow light and a limits halt result in a blinking yellow light and a hardware stall resulting in a S.O.S. blinking light (for examples) would be a nice feature to eventually add to the CP4 firmware.

On Fri, Jul 31, 2020 at 5:01 AM uncarollo2 <chris1011@...> via groups.io <chris1011=aol.com@groups.io> wrote:

'm afraid to repeat these tests as there could be potential problems with the hardware,
The "Motor Stall" warning will occur when unsafe limits are exceeded. This is not a warning that something is wrong with the motor or electronics, it is simply telling you that the software has turned off the power to the motors to prevent your scope from being damaged. At this time we use the same error code for all situations where the motor power has been turned off. It probably could be changed to indicate not "motor stall" but "motor power deactivated".  However, we have many other software challenges right now and this one will have to wait a bit. Be assured that nothing bad has happened to your electronics or the motors.

Rolando


-----Original Message-----
From: Leo Shatz <leonid.shatz@...>
To: main@ap-gto.groups.io
Sent: Fri, Jul 31, 2020 6:22 am
Subject: [ap-gto] Testing homing limits resulted in motor stall errors with Mach1 #APCC

Hello,

Recently I had a very good remote session with Howard Hedlund from A-P, who helped me to setup meridian and homing limits. I did some tests following the session and I've got some issues I'd like to raise here:

Meridian flips were fine, I didn't run in any problems with flips going the wrong way, as long as the red telrad circle was staying within meridian limits. However, I had motor stall event triggered a couple of times in the following situations:
 
- I've defined an action of "stop tracking and slewing and park in place" in homing limits and let the mount perform unsafe pier flip. When it hit the homing limit (well before colliding with the pier), the mount stopped, the message saying that limit was reached and dialog box flushing. Few moments after that, since SGP was configured to perform parking on its own, it tried to perform parking but failed as mount was already parked. I've seen a yellow flashing sign in APCC indicating an error and there was freshly triggered "motor stall" event.
 
- I did the slow slew (at rate x200) to move CWs up higher until it reached the homing limits, the mount stopped again with a message from APCC and there was another motor stall event.

After both cases I was able to unpark the mount and perform slewing in both axis (without manually turning power off/on to the mount).
 
I'm afraid to repeat these tests as there could be potential problems with the hardware, although it looks to me more like a software glitch under these circumstances. I hope it's not actually caused by a physical issue with the mount, but possibly a software issue where there is some race condition in detecting abrupt change in motor speed and control signal stopping the slewing/tracking at horizon limit.

Leo Shatz