negative power terminals should be connected with low resistance wire.  Alternatively, 

electrically isolated power supplies or batteries can be used. 

6.1.2  Settings 

Except when querying GPS units, Gemini' s serial port is set to communicate at 9600 

baud (9600 bps), no parity, 8 data bits, 1 stop bit. You must configure the COM port of 

the connected computer to match these settings. In addition, the handshake protocol 

setting for the COM port should be set to   None   (neither hardware nor software 

handshake).  Most planetarium programs perform these settings automatically for you. 

6.1.3  Troubleshooting 

If you cannot communicate with the Gemini after checking the wiring, you can use 

Gemini' s Debug Mode to find out if serial data is being received correctly. In this mode, 

the commands received (without their numeric parameters) are stored in the Information 

Buffer and can be displayed using the "Show Information" menu item. 

At the PC side, any terminal emulation program such as HyperTerm under Windows, or 

MiniCom under Linux can be used.  Connect to the COM port after setting the 

parameters as described above and type some commands from the serial command set 

like :P#, :GR# or :GD# on the PC.   Gemini should send characters in response. 

If there is no response displayed, use Gemini' s   Show Information   command to check 

whether or not Gemini received the commands sent. If not, try the following steps: 

Connect PC and Gemini with a minimum of cabling and hardware.  Use a short 

cable. 

Double check the settings of the serial port. 

Make sure Gemini started up correctly and the startup process is finished 

(otherwise most commands will not be recognized). 

Make sure no other program (planetarium program, ActiveSync,...) is accessing 

the port. 

Make sure the port is not redirected to IrDA. 

If Gemini is still not receiving commands, try different settings of the   Send Buffer 

FIFO   in the Extended Settings for the COM port of the PC. 

Once the commands reach Gemini, the response should be seen quickly. If not, try the 

other possible settings of the Receive Buffer FIFO. 

6.2  Serial Command Sets 

6.2.1  Meade  LX200 Commands 

Gemini supports a subset of the LX200 command set that is necessary for the control of 

German Equatorial Mounts. The majority of these commands start with a colon   :   and 

end with a hash mark  #  .  Each character received is stored into a buffer. After the hash 

(or an ACK character) is received, Gemini interprets and executes the command(s).  

Gemini Users Manual 

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