Watlow Series 734 Data Communications - Manual (Page 6)

How to Use Data Communications
6
WATLOW Series 733/734
EIA-485
˜
NOTE:
The Electronic
Industry Associa-
tion EIA/TIA-485
standard recom-
mends a maximum
4000 ft. total net-
work distance.
Figure 3 -
EIA/TIA-485 Inter-
face, Pin Designa-
tions.
EIA/TIA-485 Interface Pinouts
73xx-xxxx-xDxx
The EIA/TIA-485 communications uses a two wire (half duplex) system. There are
only two lines, both lines used for transmitting and receiving. Only one device, the
computer or the control, can be speaking at a time. The Series 733/734 requires a
7 millisecond delay between transmission and receipt of data. With EIA/TIA-485
you can have from one to thirty-two Series 733/734 controls connected to a com-
puter.
This diagram is a typical wiring example. The connections on the host computer
may vary depending on models. See page 7 for information about serial interfaces.
Refer to your computer user's manual for more information.
Connecting the Control and the Computer
Remove power from both the Series 733/734 and your computer before connecting
them together. This prevents noise or static interference from entering the data
communication lines. Assemble a cable and the appropriate wiring at your com-
puter. Refer to the wiring on pages 4 through 6. As soon as you connect the data
communications lines, you may apply power to your system.
12
11
10
9
8
7
6
5
4
3
2
1
12
11
10
9
8
7
6
5
4
3
2
1
Twisted Pair Wire
Twisted Pair Wire
Common Pin 8
Common Pin 8
B
A
Gnd.
EIA/TIA-485
Interface
Series 733
#1
Series 733
#2
T+ / R+
T- / R-
Com
T+ / R+
T- / R-
Com
T+ / R+
T- / R-
Com