Serial Interface Specifications68 Apollo SL30 Installation ManualExample message:$PMRRV28?PMThis example command would set the standby VOR frequency to 111.800 MHz. This isinterpreted by noting that the ASCII ‘?’ corresponds with 3Fh, +30h = 7Bh, converted to decimalequals 111 for the MHz portion. The kHz portion converts ASCII ‘P’ to 50h, -30h yields 20h,x25 kHz steps = 800 kHz. This command would also set the receiver function to monitor, so thereceiver would time-multiplex the active and standby VOR channels to track both stations.Note: The SL30 will check input frequencies for validity. An RS-232 serial error message outputwill be generated if the frequency is invalid.S ET S TANDBY COMM FREQUENCY AND TRANSCEIVER FUNCTIONThis message is used to set the standby COMM frequency.Message format:“V”.................Message class. This is a VHF NAV message.“29”................Message identifier.mk ..................Standby COMM frequency:m = desired frequency in MHz in hexadecimal, where m = desiredfrequency - 30h, with desired frequency in range of 118 to 136 MHz, or162 MHz.k = desired frequency in kHz, where k = (desired frequency / 25 kHz) +30h, with desired frequency in range of 000 to 975 kHz in 25 kHz steps.a......................Transceiver function: N = normal, M = monitor, 0 = unchanged.Example message:$PMRRV29G4MThis example command would set the standby VOR frequency to 119.100 MHz. This isinterpreted by noting that the ASCII ‘G’ corresponds with 47h, +30h = 77h, converted todecimal equals 119 for the MHz portion. The kHz portion converts ASCII ‘4’ to 34h, -30h yields4h, x25 kHz steps = 100 kHz.Note: The SL30 will check input frequencies for validity. An RS-232 serial error message outputwill be generated if the frequency is invalid.S ET ACTIVE COMM FREQUENCY AND TRANSCEIVER FUNCTIONThis message is used to set the Active COMM frequency as well as the COMM transceiverfunction.This message is only available in normal mode.Message format:“V”.................Message class. This is a VHF NAV message.
