Lexicon MC-12 用户指南
Lexicon
MC-12 Serial Communications Protocol
MC-12 Serial Communications Protocol
Printed on: 07/13/05
5 Physical Layer
5.1 DB-9 RS232 Connector
MC-12
COM1
5
3
2
9 Pin D-Shell (male)
Ground
Transmit Data
Receive Data
5
3
2
5
3
2
5
3
2
Host
Receive Data
Transmit Data
9 Pin D-Shell (female)
Ground
9 Pin D-Shell (female)
9 Pin D-Shell (male)
Note: The wiring requirements for a 9 pin to 9 pin serial connection, are a male to female straight through
cable.
5.2 Serial Port Driver
MC-12 serial port has been setup to operate as follows:
Operating Mode:
Full Duplex
Baud rate:
19.2K baud
Data Size:
8 bits (1 byte)
Parity:
Odd
Stop Bits:
1
Hardware Handshaking:
None
5.3 Errors
The MC-12 will detect parity, framing and data overrun errors. If any of the physical layer errors are
detected, the complete packet is corrupted and the MC-12 will reset the transaction and begin to look for a
start of packet byte.
detected, the complete packet is corrupted and the MC-12 will reset the transaction and begin to look for a
start of packet byte.
5.4 MC-12 Receive Buffer
The MC-12 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 MC-12 will be ignored. Therefore, making the currently transmitted packet, if partially
transmitted invalid.
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 MC-12 will be ignored. Therefore, making the currently transmitted packet, if partially
transmitted invalid.
5.5 MC-12 Hardware Verification (V1.10, Not Supported in MC-12 V1.00, V1.01)
This test verifies the RS232 ports are working by comparing the transmitted signal (at pin 2) to the
received signal (at pin 3). The MC-12 transmits a known test signal just following a power up. The MC-12
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 MC-12 labeled “RS232”. The wraparound plug shorts pins
2 to 3, allowing for the MC-12 to receive the signal it is transmitting. Once installed, power cycle the MC-
12 and verify the following message is displayed on the FPD:
received signal (at pin 3). The MC-12 transmits a known test signal just following a power up. The MC-12
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 MC-12 labeled “RS232”. The wraparound plug shorts pins
2 to 3, allowing for the MC-12 to receive the signal it is transmitting. Once installed, power cycle the MC-
12 and verify the following message is displayed on the FPD:
© 2005 Harman Specialty Group All rights reserved.
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