RKI Instruments Digester Gas Monitor - Manual (Page 19)

Digester Gas Monitor Operator’s Manual Internal Description • 13
main PCB (see Figure 5 on page 12). These four 11-point terminal strips facilitate
wiring connections to the detectors. They also provide terminals to connect a
recording device to a 4 to 20 mA output for each channel. The top terminal strip is for
channel 1 connections and each subsequent strip is used for the next channel with the
bottom terminal strip being for channel 4 connections. The Digester Gas Monitor
detectors are factory wired to the terminal strips.
• Channel Alarm Terminal Strip
A channel alarm terminal strip is located to the right of the channel 4
detector/transmitter terminal strip (see Figure 5 on page 12). This 24-point terminal
strip facilitates wiring external alarm devices (horn, light, etc.) to relay contacts that
are field configurable for alarm levels and operation and are controlled by individual
channels. The contacts are labelled NO (normally open), NC (normally closed),
and C (common). See “Viewing and Changing Global Parameters” on page 47 and
“Viewing and Changing Channel Parameters” on page 51 for instructions to configure
the operation of these contacts.
• Common/Channel Alarm Terminal Strip
The common/channel alarm terminal strip is located in approximately the middle of the
main PCB above the channel alarm terminal strip. The terminals for relays A, B, C,
and D are factory wired and are not available for customer use. Only the fail relay
terminals are available for customer use. The contacts are labelled NO (normally
open), NC (normally closed), and C (common).
• Controller Terminal Strip
The 9-point controller terminal strip is along the lower right side of the main PCB (see
Figure 5 on page 12). The controller terminal strip facilitates various internal and
external wiring connections. Table 3 lists the function of each terminal.
Table 3: Terminal Assignments for the Controller Terminal Strip
Terminal Connects to:
DP SW
DP SW Flow switch (factory wired)
EXT DC/24V BATT +
+ connection from 24 VDC power source
1
(or 24 V backup battery)
1
EXT DC/24V BATT -
- connection from 24 VDC power source
1
(or 24 V backup battery)
1
RS-485 A
RS-485 B Allow connection of the Digester Gas Monitor to a Modbus network
RS-485 C
Alarm Reset
Reset Switch Terminals (factory wired)
Alarm Reset
Alarm Buzzer + Buzzer + connection (factory wired)
Alarm Buzzer - Buzzer - connection (factory wired)
1 If 24 VDC is used as primary power source do not make wiring connections to the AC terminal strip.