Watlow CAS - Manual (Page 40)

30 CAS User’s Guide
Installation
Configuring Communications
Your system is shipped configured for RS-232. To switch between RS-
232 and RS-485, change the jumpers as shown here.
You'll need a Phillips head screwdriver and tweezers to switch between
RS-232 and RS-485. Follow these steps:
1. Power down the unit.
2. Remove the system's metal casing. Refer to the section Changing
the Prom in the Troubleshooting chapter of this manual.
3. Find jumpers JU2, JU3, JU4, and JU5 (above).
4. (This part of the explanation assumes that you're changing the com-
munications from RS-232 to RS-485. If you're not, follow the next
two steps but move the jumpers from the B position to the A posi-
tion.) Use tweezers to carefully grasp the jumpers and gently slide
them off the pins.
5. Use tweezers to gently slide the jumpers onto the B pins. Move
jumpers JU2, JU3, JU4, and JU5 to the B position, as shown above.
6. If you have changed the system to 485 communications, put the 200
ohm terminating resistor on the RX line of the last monitor in the
system. (If you're only using one monitor, it's the last monitor in the
system.) Place jumper JU1 in the B position . All other monitors in
the system should have JU1 in the A position.
7. Put the casing back on.
JU2
JU3
JU4
JU5
A
RS-232
Configured for RS-232 Configured for RS-485
A
RS-232
B
RS-485
B
RS-485