RKI Instruments M2A - Manual (Page 16)

11 M2A Transmitter Operator’s Manual
to program the M2A. On the combustible and CO
2
versions of the M2A, a factory adjust pot just
above the programming connector is used to set the detector current.
Power/Signal Terminal Strip
The power/signal terminal strip is a three position plug-in style terminal strip located at the top of
the left terminal column. It is used to connect 24 VDC power to the M2A and to connect the 4 - 20
mA output signal to a device.
The signal output, the S terminal, does not have to be connected for the M2A to function. The S
terminal is used if you want to connect the 4 - 20 mA output signal to another device such as a gas
monitoring controller, chart recorder, or programmable controller (PLC).
Detector Terminal Strip
The detector terminal strip is a four position plug-in style terminal strip and is the middle terminal
strip in the left terminal column. For a combustible or CO
2
M2A, all four terminals are used to
connect the detector to the M2A. For a toxic or oxygen M2A, only two of the terminals are used for
connecting a detector: two terminals are dedicated for connecting a toxic detector and two are
dedicated for connecting an oxygen detector (only one detector can be installed).
Figure 10: Detector Terminal Strip
NOTE: The detector is factory-wired to the M2A. See “Wiring the M2A Transmitter” on
page 18 for all wiring procedures related to M2A.
Modbus Terminal Strip
The Modbus terminal strip is a three position plug-in style terminal strip and is the bottom terminal
strip in the left terminal column. It allows connection of the M2A into a Modbus network.
Toxic/Oxy
Detector
Terminal
Strip
Comb/CO2
Detector
Terminal
Strip
C
NC
NO
AL
AR
M 1
C
NC
NO
AL
AR
M 2
C
NC
NO
FA
IL
-
S
+
A
B
C
R
S
485
PW
R
/SI
G
R
W
G
B
LE
L
-
S
+
A
B
C
R
S
485
PW
R
/SI
G
R
W
G
B
LE
L
C
NC
NO
AL
AR
M 1
C
NC
NO
AL
AR
M 2
C
NC
NO
FA
IL