Nexstar SynScan instruction manual Additional RS232 Commands, Physical Connection Diagram

Physical Connection Diagram

RJ-11 Connector

RJ-11

NC

RD

GND

NC

TD

NC

II

The Back of the DB9 Pinout

I

9

Additional RS232 Commands

Sending a track rate through RS232 to the hand control

1.Multiply the desired tracking rate (arc seconds /second) by 4. For example: if the desired track rate is 120 arc seconds/second (proximately 8 times of sidereal rate), then the TRACKRATE = 480.

2.Separate TRACKRATE into two bytes, such that (TRACKRATE =

3.TrackRateHighByte"256 + TrackRateLowByte). For example TRACKRATE = 480, then TrackRateHighByte = 1, TrackRateLowByte = 224.

To send a tracking rate, send the following 8 bytes:

a.Positive Azm tracking: 80, 3, 16, 6, TrackRateHighByte, TrackRateLowByte, 0, 0

b.Negative Azm tracking: 80, 3, 16, 7, TrackRateHighByte, TrackRateLowByte, 0, 0

c.Positive Alt tracking: 80, 3, 17, 6, TrackRateHighByte, TrackRateLowByte, 0, 0

d.Negative Alt tracking: 80, 3, 17, 7, TrackRateHighByte, TrackRateLowByte, 0,0

4.The number 35 is returned from the hand control.

Sending a slow-Goto command through RS232 to the hand control

1.Convert the angle position to a 24bit number. Example: if the desired position is 220?, then POSITION-24BIT = (220/360)*224 = 10,252,743

2.Separate POSITION-24BIT into three bytes such that (POSITION-24BIT = PosHighByte * 65536 + PosMedByte * 256 + PosLowByte). Example: PosHighByte = 156, PosMedByte = 113, PosLowByte = 199

3.Send the following 8 bytes:

a.Azm Slow Goto: 80, 4, 16, 23, PosHighByte, PosMedByte, PosLowByte, 0

b.Alt Slow Goto: 80, 4, 17, 23, PosHighByte, PosMedByte, PosLowByte, 0

4.The number 35 is returned from the hand control.

Reseting the position of Az or Alt

1.Convert the angle position to a 24bit number, same as Slow-Goto example.\

2.Send the following 8 bytes:

a.Azm Set Position: 80, 4, 16, 4, PosHighByte, PosMedByte, PosLowByte, 0

b.Alt Set Position: 80, 4, 17, 4, PosHighByte, PosMedByte, PosLowByte, 0

3.The number 35 is returned from the hand control.