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A. Format
Communications between the VMU and the VSCU take place over an RS-232C
serial link:
Communication Standard: EIA RS-232C
Bit Rate: 1200 bits per second
Start Bit: 1
Data Bits: 7 (ASCII characters)
Parity Bit: 1 (even parity)
Stop Bit: 1
B. General
(1) All commands (from VSCU to VMU) start with the @ character.
(2) All status messages (from VMU to VSCU) start with the & character.
(3) The format uses space characters (ØD Hex) as shown.
(4) Commands and status messages terminate with the Carriage Return
character <CR>.
(5) Commands failing the character parity check cause the command to be
rejected.
(6) Status request commands cause the VMU to output the appropriate
status message. No status messages are be sent unless specifically
requested to do so.
(7) KEY:
Space Character (ØD Hex)
<CR>: Carriage Return Character (ØD Hex)
NN: Channel No. (Ø1 to 12)
FFF: Frequency (programmed frequency is FFF.25 MHz)
NOTE: The value of FFF is 139 to 295 for RD-AA5002-12, and 090 to
345 for RD-AA5002-22/-23/-25.
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PART NUMBER RD-AA5002 SERIES
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C. Frequency Command (VSCU to VMU)
Format: @NN FFF<CR>
Commands VMU to change channel NN to a frequency of FFF (+0.25 MHz)
example: @01 151<CR>
Commands the VMU to set channel 1 to a frequency of 151.25 MHz.
Response from VMU:
&NN FFF.25<CR> Channel has been changed to new freq.
&NN FFF.25 FAULT<CR> Channel has a fault.
&ERR Ø<CR> Parity error.
&ERR 1<CR> Channel range error.
&ERR 2<CR> Frequency range error.
&ERR 3<CR> Duplicate error (another channel already
assigned to frequency).
D. Delete Channel Command (VSCU to VMU)
Format: @NN ØØØ<CR>
Commands VMU to delete channel N2 from the expected channels. This
command is given if the VMU contains less than 12 modulator cards, and
prevents the microcontroller from endlessly trying to program modulator
cards which are not present.
example: @12 ØØØ<CR>
Commands the VMU to delete channel 12 (modulator card 12) from the
expected number of channels.
Response from VMU:
&ERR Ø<CR> Parity error.
&ERR 1<CR> Channel range error.
No response is sent for a valid command.
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PART NUMBER RD-AA5002 SERIES
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E. Single Frequency Status Request Command
Format: @NN?<CR>
Commands the VMU to send to the VSCU the frequency of channel N1N2.
Example: @Ø8?<CR>
Requests the frequency of channel 8.
Response from VMU:
&NN FFF.25<CR> Channel NN is at a frequency of FFF.25 MHz.
&NN ØØØ<CR> Channel NN has been deleted.
&NN FFF.25 FAULT<CR> Channel NN, programmed for a frequency of
FFF.25 MHz, is faulted.
F. All Frequencies Status Request Command
Format: @SR?<CR>
Commands the VMU to send to the VSCU the frequencies of all channels.
Response from VMU:
The VMU will send sequentially the status of all channels, e.g.,
&Ø1 FFF.25<CR> The frequency of channel 1 is FFF.25 MHz.
&Ø2 ØØØ<CR> Channel 2 has been deleted.
&Ø3 FFF.25 FAULT<CR> Channel 3 has been programmed for a
frequency of FFF.25 MHz, but is faulted.
VMU will continue to channel 12.
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COMPONENT MAINTENANCE MANUAL
PART NUMBER RD-AA5002 SERIES
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G. TEST VIDEO Commands
Format: @TEST<CR>
Switches the input to modulator card 1 (Channel 1) to the TEST VIDEO
input.
Format: @NORM<CR>
Switches the input to modulator card 1 (Channel 1) to the CH1 VIDEO
input.
There is no response from the VMU.
H. TEST VIDEO Status Request Commands
Format: @VIDEO?<CR>
Requests the status of the TEST VIDEO input.
Response from VMU:
&TEST<CR> Channel 1 input is TEST VIDEO
&NORM<CR> Channel 1 input is CH1 VIDEO
&ERR Ø<CR> Parity error in the @TEST<CR> TEST
VIDEO command (see G. above.)
I. Video Signal Generator Commands
Format: @BION<CR>
Switches the input to modulator card 2 (Channel 2) to the Video Signal
Generator.
Format: @BOFF<CR>
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COMPONENT MAINTENANCE MANUAL Video Modulator Unit (VMU)(24)
