BIRD THRULINE 4021, Instruction Book

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Chapter 5 RS-232 Interface
This chapter discusses setup of the RS-232 interface module and
describes the RS-232 commands that apply to the Bird 4421.
Operators should understand EIA Standard RS-232-C and have basic
computer programming skills before writing any programs.
Description
The Bird 4421 RS-232 interface module is a plug-in board that can be
factory or field installed. An eight-position DIP switch is used to set
operational conditions such as baud rate, parity, and stop bits. The
current bus status is displayed on the bottom line of the display.
Cable Connector
The interface module uses a standard 25-pin RS-232 connector. Pin
assignments are listed in Figure 23. If the controller uses a different
wiring arrangement, do not attempt to rewire the interface module’s
connector. A null modem kit should be used for rewiring instead.
Indicators
The bottom line of the power meter’s display shows indicators
describing the status of the Bird 4421 when used with the RS-232
interface. These are:
TALK:
When TALK is displayed, the power meter is transmitting
data. This is always shown when the unit is in “talker-only” mode.
LISTEN:
When LISTEN is displayed, the power meter is receiving
data.
Figure 23
RS-232 Pin
Assignments
Pin Designation Notes
1
Protection Ground Chassis Ground
2
Transmit Data
3
Receive Data
4
Request to Send (Output) Set true after module power up
5
Clear to Send (Input) Set by input device. When true, it
enables the module to transmit. When
false, it disables transmission.
6
Data Set Ready (Input) Set internally true by module
7
Signal Ground Return path for data and control signals
8
Receive Signal DET (Input) Set true by module
20
Data Terminal Ready (Output) Set true after module power up