4
GTOCP5 CONTROL BOX – YOUR MOUNT’S BRAIN
Your mount is a unique combination of precision, intelligence and strength. The heavy-duty, CNC machined parts give the
mount the strength and rigidity to hold a load in a rock-steady fashion while exposed to the elements and while that entire
load is in motion. The precision of every component allows accuracies that are measured in fractional arc seconds. The
intelligence to control all of this is in the GTO Micro-step Servo System.
There are three major sub-systems to the GTOCP5 Micro-step Servo System:
1. The GTOCP5 Control Box This is the real “brain” of your mount. Please try to understand this from the outset. Your
mount is NOT controlled by the Keypad or by your computer. They merely serve as input devices and convenient inter-
faces for you, the user. The GTOCP5 serves the following functions among others:
○It provides the voltage to drive the motors.
○It determines the motors’ rotational direction,
rotational speed and the total number of rotations
required to arrive at the destination coordinates
that are commanded.
○It maintains the accurate tracking speed that is
chosen and applies any needed corrections from
the absolute encoder feedback.
○It takes the provided input and translates it into
the correct actions that fulll our wishes.
○It seamlessly integrates the encoder and limit
functions with the regular servo control functions
for an unprecedented level of control.
○It bears repeating: It is the GTOCP5 control box
that controls the mount!
2. The Micro-step Motors and Absolute Encoders of the Mach2GTO. These DC micro-step motors are the work hors-
es that actually move the mount. Their integration with the absolute encoders provide the necessary feedback informa-
tion for the GTOCP5 to perform its varied operations. The encoders working with the microprocessor in the GTOCP5
operate to an accuracy of 0.05 arc seconds per step. These motors can be accurately controlled over a speed range of
4800:1, which allows 1.0x sidereal for guiding to 1800x sidereal for 7.5 degree per second slewing.
3. An External Input Device to Interface with the User. In order to control the movement of the mount, you will need
to connect at least one of the devices below. For more information, refer to "Controlling Your GTOCP5 Mount" on page
20.
○Computer with a planetarium program or observatory control software. The AP V2 ASCOM Driver and the
"The Astro-Physics Command Center - Standard & Pro Versions" on page 27 are both included with your
mount. APCC provides advanced functionality and safety features in addition to the ability to create tracking
and pointing models.
○Mobile smart device with mount command functions that employ the Astro-Physics Command Protocol. For
more information, see "Workow When Using Mobile Smart Devices" on page 34.
○Keypad (optional)
To ensure the reliability of this control equipment, the Astro-Physics Micro-step Servo System uses industrial components.
We chose a sturdy industrial handheld computer as our keypad. These components are far more rugged than
conventional consumer electronics, and they will continue to function properly well below zero degrees F (-18 C). The
optional Keypad uses a vacuum uorescent display that does not lose its speed or readability in the coldest winter
conditions...all the way down to -40 degrees F (-40 C). However, if you plan to use your mount in extreme temperatures
and conditions, please contact Astro-Physics rst.
All of this control and sophistication is accomplished in an incredibly ecient manner. The Micro-step Servo System can
be operated from 12-24 volt DC power source. Using 24 volts provides the added advantage of higher slew speeds.
