Emerson Process Management 3420 Carbon Monoxide Alarm User Manual


 
Reference, Installation, and Operations Manual Section 5: Startup and meter configuration
3-9000-743 Rev S June 2013
RS-485 serial connection setup 115
b. To configure Port A for RS-485 Half Duplex operation, set the CPU board and
Field Connection board switches as indicated in the table below (see Figure 3-24
for switch bank locations):
Table 5-7 Serial Port A RS-485 half duplex configuration switch settings
Board Switch Position
CPU S3-1 RS485
S3-2 RS485
S3-3 RS485
S3-4 RS485
S5-1 HALF
S6-1 RS485
S6-2 RS485
Field Connection Termination ON Termination OFF
S1-1 TERM ON TERM OFF
S1-2 TERM OFF TERM OFF
S1-3 HALF DUPLX
S1-4 HALF DUPLX
Termination should only be enabled if the meter is the last drop in a multi-drop
configuration or the only meter in a single-drop configuration.