Serial Interface Communication Protocol; General Specifications; Protocol Definition; Communication Characteristics - Philips BDL4221V User Manual

3. Serial Interface Communication Protocol

3.1 General specifications

3.1.1 Protocol definition

Communication to the main monitor microprocessor is possible through the serial port,
which support a communication protocol dedicated to BDS only. The protocol is
specifically designed to allow data communication in half duplex multi-point
environments, but it can also be used for half duplex point-to-point RS-232
communication.

3.1.2 Communication characteristics

A half duplex communication is implemented starting from the concept of a master-slave
structure, where the monitor is supposed to be the slave.
The first action is always taken by the master, which can be either a built-in PC-based
video controller in a MASTER monitor or any external device (acting a server) interfaced
to the monitor. After sending a command or a request in the appropriate format (see
section 3.2), the master receives form the slave an acknowledgement, which tells the
transmitter whether the command is not valid (or not executable, anyway) or it is
accepted.
In case of a request, the requested information is sent back and it becomes the
acknowledgement by itself.
If the poll sequence has been sent, the acknowledgement tells the transmitter the
monitor status, i.e. whether it is ready or busy and other information.

3.1.3 RS232 pin assignment

There is a 9-pin male connector on the set for RS232 communication. The pin
assignment is as following table.

3.1.4 RS232 settings

This section describes the parameters used during the whole communication process.
Baud rate
Data bits
Parity
Stop bit
Flow Control
[ NAME ]
2838 100 05424
Pin No.
1
2
3
4
5
6
7
8
9
57600 bps
8 bits
None
1
None
Philips
Function Description
GND Signal Ground
RxD Receive Data
TxD Transmit Data
NC Not Connected
GND Signal Ground
NC Not Connected
NC Not Connected
NC Not Connected
NC Not Connected
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