GASMAX II Operation & Maintenance Manual, Revision 7.0
Page 21
CONNECTING AN EXTERNAL 4-20MA INPUT DEVICE (CH 2)
The GASMAX II can be factory configured to support a general purpose, non-isolated 4-20mA input on
channel 2. Power Supply boards that have been converted to 4-20mA will have TB1 marked to indicate
PWR (+24V), 4-20 IN (signal) and COM (ground). The amount of voltage and current available for the
remote 4-20mA device is determined by the GASMAX DC supply connected to TB2. Note that in this case,
channel 1 is still available to support a local or remote toxic sensor. The calibrated output for channel 2 is
available on TB2, Pin 3.
NOTE: Poured seals and rigid conduit are required if the remote sensor is installed in a hazardous area.
WARNING:
IO / POWER SUPPLY BOARDS THAT HAVE BEEN CONVERTED TO 4-20MA WILL NOT SUPPORT
LOCAL OR REMOTE BRIDGE-TYPE SENSORS. ATTACHING A BRIDGE-TYPE SENSOR WILL DAMAGE OR
DESTROY THE SENSOR.
Figure 3-14: Remote 4-20mA Input (Ch 2)
ibbon to isplay
I Power upply
-
m Input
P
I
C
M
P
T
T
G
TB
TB
PWR => +24VDC (from TB2-1)
420 IN => Channel 2 Analog Input
COM => Common (from TB2-4)
TB2
–
1: +24VDC Input
TB2
–
2:
Channel 1 4-20mA Out
TB2
–
3:
Channel 2 4-20mA Out
TB2
–
4: Power / Signal Common
10-0233-420
I/O Power Supply with 4-20mA In