Appendix C: RS-232
Connection
The Atlas
Additional RS-232 Commands
Sending a Tracking Rate
1.Multiply the desired tracking rate (arcseconds /second) by
4.For example: if the desired track rate is 120 arcseconds/ second (approximately 8 times sidereal rate), then the TRACKRATE = 480.
2.Separate TRACKRATE into two bytes, such that (TRACKRATE = TrackRateHighByte*256 + TrackRateLowByte). For example, if TRACKRATE = 480, then TrackRateHighByte = 1 and TrackRateLowByte =
3.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 controller.
Sending a Slow-GoTo Command
1.Convert the angle position to a 24 bit 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 controller.
Resetting the Position of Azimuth or Altitude
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 controller.
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