Watlow 988 series - Wiring Diagrams

2.2
Data Communications with the Watlow Series 988 Family
Hardware and Wiring, Chapter 2
• • • • •
1 2 3 4 5
6 7 8 9
• • • •
RS-232 Interface Wiring
The RS-232 communications uses a three-wire, full-duplex system. There is a
separate line for transmitting data, a line for receiving data and a common line
between the computer and the controller. With RS-232 you can have only one
controller connected to a single computer.
This diagram is a typical wiring example. The connections on the host computer
may vary, depending on the model. Refer to your computer or serial card user's
manual for specific information.
Wiring
Transmit 5
Common 7
Single Controller
DB-9 female viewed from wire side
(typical connections with jumpers)
Receive 6
Figure 2.2 -
RS-232 Interface
Wiring Diagrams.
DB-9 Pinouts
1 DCD
2 receive
3 transmit
4 DTR
5 common
6 DSR
7 RTS
8 CTS
• • • • • • • • • • • • •
1 2 3 4 5 6 7 8 9 10 11 12 13
14 15 16 17 18 19 20 21 22 23 24 25
• • • • • • • • • • • •
Common 7
Transmit 5
Single Controller
DB-25 female viewed from wire side
(typical connections with jumpers)
Receive 6
DB-25 Pinouts
2 transmit
3 receive
4 RTS
5 CTS
6 DSR
7 common
8 DCD
20 DTR
NOTE:
The Electronic
Industry Association
(EIA) RS-232
standard recom-
mends a maximum
50-foot total point-
to-point distance.
Communications Wiring
The rest of the chapter explains how to connect your controller to a computer.
Consult the instruction manual for your computer's serial port or serial card for
detailed serial port pin information. Industrial environments often contain a lot of
electrical noise. Take care to isolate your control system.