BIRD THRULINE 4020 series, Instruction Book

Page: 41 / 74

29
Chapter 5 RS-232 Interface
This chapter discusses setup of the RS-232 interface feature 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 feature is an integral part of the I/O hub cir-
cuit board inside of the mm21. An eight-position DIP switch is used to set
operational conditions such as baud rate, parity, and stop bits. The bottom
line of the display indicates the current bus status.
Cable Connector
The interface uses a standard 25-pin RS-232 connector. Pin assignments are
list ed in F igu r e 24. If t h e con t r oller u ses a different wiring arrangement, do
not attempt to rewire th
should be used for rewiring instead.
Indicators
splay 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
LISTEN:
When LISTEN is displayed, the power meter is receiving data.
Figure 24
RS-232 Pin
Assignments
Pin Designation Notes
1
P r ot ect ion Gr ou n d Ch a ssis Gr ou n d
2 Tr a n sm it Da t a
3
Receive Da t a
4 Requ est t o Sen d (Ou t pu t ) Set t r u e a ft er m odu le power u p
5
Clea r t o Sen d (In pu t ) Set by in pu t device. Wh en t r u e, it
en a bles t h e m odu le t o t r a n sm it . Wh en
fa lse, it disa bles t r a n sm ission .
6
Da t a Set Rea dy (In pu t ) Set in t er n a lly t r u e by m odu le
7 Sign a l Gr ou n d Ret u r n pa t h for da t a a n d con t r ol sign a ls
8
Receive Sign a l DE T (In pu t ) Set t r u e by m odu le
20 Da t a Ter m in a l Rea dy (Ou t pu t ) Set t r u e a ft er m odu le power u p