Watlow Series 942 Data Communications - Manual (Page 7)

How to Use Data Communications
7
WATLOW Series 942
Control Chassis - Top View
Network Connections
You can connect a data communication equipped Series 942 to any computer
with an RS-422A or RS-423A (RS-232C compatible) or EIA-485 serial inter-
face. The serial interface is the key. The IBM™PC® with an RS-232C serial
output card, for instance, will talk to a single RS-423A equipped Series 942.
For a multiple 942 network with the same PC, you'll need an RS-232 to RS-422
converter to act as a "bus," or multiple connection point.
A Watlow recommends the Burr-Brown LDM 422 for that purpose.
The address is: Burr-Brown, Inc., 1141 West Grant Rd,. Suite 131,
Tucson, AZ 85705, Phone: (602) 624-2434, Fax: (602) 623-8965.
B For EIA-485, we recommend the Black Box LD485A. Their address is:
Black Box Corporation, Mayview Road at Park Drive, Box 12800,
Pittsburgh, PA 15241, Phone: (412) 746-5530.
Figure 4 -
RS-422A/RS-423A
Switch Selection.
(Up) RS-423A
(Down) RS-422A (Up) RS-423A
(Down) RS-422A
NOTE:
The Series 942
leaves the factory in
RS-423A operation
(C1).
Configuration
How to Set the Hardware Protocol Switches
for 942A-XXXX-B000 Units Only
The RS-422/RS-423 switches are on the Communication Module Board
(A007-1830). Figure 4 shows the location of this board. You can select both
C1 switches for RS-423 or both C2 switches for RS-422 operation. Both
switches must be set the same for the desired protocol.
To change the position of a switch, remove the power from the Series 942 and
turn the front panel locking screw 90
°
counterclockwise. To remove the
control chassis, grip the front panel bezel and pull it straight out from the
control case. Set both switches the same, C1 (towards you for RS-423) or C2
(away from you for RS-422) then return the control chassis to the case. Be
sure it is oriented correctly. Press firmly, but gently, to seat the chassis.
Secure the front panel locking screw and reapply power.