Pioneer VSX-82TXS Service Manual page 3

Notice1
To meet stringent power conservation measures Pioneer A/V receivers consume less
than 1 Watt when in the "Standby" or "Off" mode.
To achieve this the main CPU doesn't operate in Standby/Off.
For this reason the receiver may not understand the first command send to it's the RS-232C port
but the main CPU will "wake up" with the first command.
In other words, the receiver is using the first command as a trigger to wake up the main CPU
and may not respond correctly to it.
For the proper execution of the first command please send the command twice.
Also, please make sure to have at least a 100msec. interval between the first and second command.
Example1
PO<CR>
↓
100msec Wait
↓
PO<CR>
Notice2
It takes a brief amount of time for the receiver to respond to a command like "Surround Mode"
from your control system.
When the receiver receives a command it writes that information to the EEPROM.
Accordingly, you have to keep at least 100msec. before you do a "TIMEOUT" after sending the command to the receiver.
Example2
SR: The receiver's response to the command for PRO LOGIC II MUSIC.
Control System
014SR<CR>
Confirmation
Notice3
The interval between each response sent from the receiver is 20msec.
Therefore you have to wait at least 20msec. before a "TIMEOUT".
Example3
?F: Responding to a request for the current function (input).
Control System
?F<CR>
Confirmation
Receiver
→ Receives the command and writes the info to the EEPROM.
↓
↓ 100msec
↓
← SR014<CR+LF>
Receiver
→ Receives the command and processes a response.
↓ 20msec
F
↓ 20msec
N
↓ 20msec
0
↓ 20msec
4
↓ 20msec
CR
↓ 20msec
← LF