Physical Layer; Db-9 Rs232 Connector; Serial Port Driver; Errors - Lexicon MC-12 V3.0 - SERIAL COMMUNICATIONS PROTOCOL DEFINITION REV 1-5 Manual

Lexicon, Inc.
MC-12 Serial Communications Protocol

5 Physical Layer

5.1 DB-9 RS232 Connector

MC-12
COM1
Transmit Data
2
Receive Data
3
5
Ground
9 Pin D-Shell (female)
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:
Baud rate:
Data Size:
Parity:
Stop Bits:
Hardware Handshaking:

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.

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.

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:
© 2003 Lexicon, Inc. All rights reserved.
9 Pin D-Shell (female)
2
3
5
9 Pin D-Shell (male)
Full Duplex
19.2K baud
8 bits (1 byte)
Odd
1
None
Printed on: 08/18/03
Host
Receive Data
2 2
Transmit Data
3 3
Ground
5 5
9 Pin D-Shell (male)
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