Comb/co, 11 m2 transmitter operator’s manual – RKI Instruments M2 Series User Manual
Page 16

11
M2 Transmitter Operator’s Manual
connector at the bottom of the terminal PCB is used to connect the terminal PCB to the
control PCB with a ribbon cable. A 5 position connector on the left side of the terminal
PCB is used by factory or field service personnel to program the M2. On the combustible
and CO
2
versions of the M2, 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 M2 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 M2 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
M2, all four terminals
are used to connect the detector to the M2. For a toxic or oxygen M2, 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 M2. See “Wiring the M2 Transmitter” on
page 18 for all wiring procedures related to M2.
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 M2 into a
Modbus network.
C NC NO
C NC NO
C NC NO
ALARM 2
ALARM 1
F
AIL
A B C
RS 485
PWR/SIG
LEL
S
R
W G B
C NC NO
C NC NO
C NC NO
ALARM 2
ALARM 1
F
AIL
A B C
A B C
RS 485
RS 485
PWR/SIG
PWR/SIG
T
O
XIC O
X
Y
T
O
XIC O
X
Y
S
S
Comb/CO
2
Detector
Terminal Strip
Oxy/Toxic Detector
Terminal Strip
A B C
RS 485
PWR/SIG
LEL
S
R
W G B