JBL Performance Series RS-232 Serial Protocol Definitions
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The AV1 will detect parity, framing, and data overrun errors. If any of the physical layer errors are detected,
the complete packet is corrupted and the AV1 will reset the transaction and begin to look for a start of
packet byte.
4.4 AV1 Receive Buffer
The AV1 has an internal receive buffer. The buffer is 256 Bytes and will transmit a NAK packet with an error
code of DC_ERR_BUFFER_FULL to the HOST if the buffer is full. If the buffer is full, all data transmitted to
the AV1 will be ignored. Therefore, making the currently transmitted packet, if partially
transmitted invalid.
4.5 AV1 Hardware Verification
This test verifies the RS232 ports are working by comparing the transmitted signal (at pin 2) to the received
signal (at pin 3). The AV1 transmits a known test signal just following a power up. The AV1 monitors the
serial port receivers while transmitting the test signal. If the signals are the same, the test passes. In order to
test this circuit, RS232 Wraparound plug(s) are needed and must be installed at the female D9 connector(s)
on the rear panel of the AV1 labeled “RS232”. The wraparound plug shorts pins 2 to 3, allowing for the AV1
to receive the signal it is transmitting. Once installed, power cycle the AV1 and verify the following message
is displayed on the FPD:
SERIAL PORT A PASSED
SERIAL PORT B PASSED
This message is displayed for about 2 seconds before entering normal operating mode. If no messages are
displayed, then both wrap tests failed.
5 Data Link Layer
The data link layer is used to define a transmission packet. The layer appends a header and tail that
encloses the transmitted application packet data. The data link header will contain the start of packet byte
and count of bytes to follow. The data link tail will contain the end of packet byte.