Be very (!!) careful when you use this system for unattended remote
operation.

It is designed to give the remote user full control of the telescope. This
means it is the end-user's responsibility to insure that the telescope does 
not move into a configuration that may damage it, or damage accessories
attached to it.

A German equatorial is particularly susceptable to collision with the pier, or
with "hard stops" on the mounting.  This driver does take these limits into
account, and attempts to keep the telescope away from the pier.  However, it
is possible that something could go wrong, and the control system
does NOT provide for failsafe operation.

In attended operation, there should be a hardware "kill" easily accessible. 
There are two reasons --

(1) Operator safety in case he or she is caught in some way by the moving
telescope.  Treat the telescope as you would any large machine and beware of
catching clothing or hair on moving parts.

(2) Instrument safety in case of collision of the moving telescope or 
its accessories with the pier or nearby equipment.


If you are using this system to control an unattended telescope, I strongly
recommend that you add mechanical switches in series with the DC supply on
the motor drive.  These switches would be normally closed, but should
instantly open if

(1) OTA points below the horizon
(2) The HA motion approaches the mounting's physical limits
(3) The Dec motion endangers attached accessories such as a camera

The OTA and declination switch could be a level switch. These are typically
simple ball-in-tube devices that trip a microswitch if the ball is at the bottom
of the tube. Mercury switches are also ideal, but not environmentally sound.

The HA limit requires two switche and they  should be mechanical (not software)
microswitches that trip when the mounting approaches an HA slew limits.  Design
the switches so that if they fail the operation will stop.  Switches which rely
on an detecting an optical transition and are not failsafe may lead to serious
mechanical damage if the wiring or the sensor itself fails. 

Recovery from a limit switch trip should require manual intervention. In a
remote system with visual confirmation of the telescope's orientation, this may
be met by a power override through a web switch or the telescope control
computer, followed by manual control of the telescope slew to clear the limit
situation and return to a safe state.  

Suggestions and examples of how to achieve this inexpensively are provided in
the manual and on-line documentation.  Use this system with the understanding
that there are serious risks to your instrument in unattended operation.