Re: Mount slewing acceleration/deceleration profile


Roland Christen
 

There is one thing that could cause a sudden stop at the end of a slew, and that is a low voltage at the terminals of the CP4. This can be caused by the power cord being too long, or by the power supply not delivering at least 12.5 volts at the CP4 terminals. What happens is that the motors cannot slew fast enough to keep up with the commanded speed and fall behind. At the end of the slew the motors are still behind and are still trying to catch up, even though the commanded rate is slowing down during the ramp down phase. The motors will then stop abruptly when the commanded position is reached. This is by no means a normal situation and needs to be resolved at the power supply.

I have seen this more than once in customer observatory setups where the 12 volt power was located some distance away and a large voltage drop occurred in the 12 volt cable feeding the mount controller.

One thing to try is to increase the voltage to the mount to 16 or 18 volts, which will reduce the current being drawn by the controller and which moves the voltage away from the 12 volt limit where problems can occur.

Roland


-----Original Message-----
From: Roland Christen via groups.io <chris1011@...>
To: main@ap-gto.groups.io <main@ap-gto.groups.io>
Sent: Tue, Apr 19, 2022 7:03 pm
Subject: Re: [ap-gto] Mount slewing acceleration/deceleration profile

What color is your light on the CP4 controller? Does it turn yellow when it finishes slewing?

Roland

-----Original Message-----
From: Craig Young <craig.young.m8@...>
To: main@ap-gto.groups.io
Sent: Tue, Apr 19, 2022 7:02 pm
Subject: Re: [ap-gto] Mount slewing acceleration/deceleration profile

I have a conference call with Mike and Dave early tomorrow on another issue which may be related.  I will bring this up at the same time.  Thanks Roland.

Craig

--
Roland Christen
Astro-Physics

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Roland Christen
Astro-Physics

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