GDS Corp. 2513 Hwy 646 Santa Fe, Texas 77510 (409) 927-2980 (409) 927-4180 fax
Quickstart Guide
GASMAX II / PID Toxic & VOC Gas Monitor
www.gdscorp.com [email protected]
IMPORTANT
-
Before installing the GASMAX II, ensure there are
NO toxic gases present. Declassify the area if necessary.
Factors such as fans, prevailing winds, convection and density must
be considered when determining location. As with all sensors, the
GASMAX II should be protected from directed water, shock, vibration
and dirt. The PID sensor should be mounted vertically.
Use installation practices approved for the appropriate area. When
installed properly, the GASMAX II with PID sensor is certified for use
in areas rated Class 1, Div 1, Groups B, C & D.
S2
Ribbon to
1 2
4
3
PW
R
OU
T
4-
20
EC
H
E
M
”
OU
T
4-
20
“L
EL”
GND
RE
F
COM
AC
T
CATBEAD
S1
C7
C8
C1
C2
I/O Power
Supply
TB1
TB2
Unscrew the cover of the GASMAX II. Loosen the thumbscrews
holding the display assembly and remove it. The power supply board
is attached to the inside of the GASMAX housing (see Figure 1).
CDC to TB2 pin 1 and –DC to TB2 pin 4. The allowable DC
voltage range is +12 to 30 VDC. The calibrated 4-20mA LEL output
signal is available at TB2 pin 3.
If an optional electrochemical sensor is connected to the GASMAX II,
the 4-20mA Echem output is available on TB2 pin 2.
Fig 1. GASMAX Power Supply Board
Fig 2. GASMAX Alarm / MODBUS
Board
I. MOUNTING LOCATION
II. POWER & 4-20mA OUTPUT WIRING
III. RS-485 DIGITAL INTERFACE WIRING
If the GASMAX II Alarm / MODBUS board is installed, it will be
attached to the GASMAX II electronics assembly (see Figure 2).
Attach the RS-485 wires to TB2 pins 1 & 2 and the shield wire to
pin 3. RS-485 is polarity-sensitive and the wires on pins 1 & 2 may
need to be swapped for proper operation. If wiring in a “daisy
chain”, terminals 4 & 5 are available for outgoing RS-485 wiring.
If necessary, select Jumper 1 (J1) position “A” to enable the RS-
485 termination resistor. This is typically done on the device
furthest from the RS-485 master controller.
U1
TB
K2
K3
K1
J
1
2
4
3
5
A
B
A
S
B
1
2
4
3
5
6
7
9
8
NO
C
N
NO
C
NC
NO
C
NC
TB
TB
A
B
+
-
J1-A - Installs RS-
485 Termination
Resistor
RS-485 “A” & “B” terminals
are connected internally. “S”
Remote Alarm Reset
Assy 10-0234
Relay
Relay 2
Relay 3
IV. SENSOR INTERFACE WIRING
If a local PID smart sensor is installed, it will be connected to
connector S1 on the GASMAX II power supply board (See Figure 1).
If a remote PID sensor is installed, it should be connected to the R,
C and A terminals on the GASMAX II power supply board (See
Figure 1). The remote sensor housing terminals are also labeled R,
C and A for easy identification.
REMOTE PID
Sensor
Power Supply &
4-20mA Output
Local PID Sensor
MODBUS Interface
ALARM Relays
