Bacharach MGS-250 Installation Manual - page 2
World Headquarters
621 Hunt Valley Circle
New Kensington, PA 15068 USA
Phone: 724-334-5000 • Fax: 724-334-5001
Toll Free: 1-800-736-4666
Website: www.MyBacharach.com
E-mail: help@MyBacharach.com
5: WIRING AND CONFIGURATION
CABLE OPENINGS: Each MGS-250 transmitter
contains two cable glands. The left cable gland
comes pre-installed, and the right cable gland is
optional and must be installed if needed. If the right
cable gland is not needed, the blanking plug (includ-
ed in the mounting kit) must be installed instead.
114A Georges Street Lower
Dun Laoghaire • Co Dublin • Ireland
Phone: +353 1 284 6388 • Fax: +353 1 284 6389
NOTE: To make wiring connections,
you must first open the MGS-250
cover panel. The cover panel
detatches by pressing the top latch
with a suitable screwdriver or other
flat blade.
NOTE: After wiring is completed,
carefully re-assemble the enclosure.
After installation is complete, be sure to
refer to the User Manual (part number
6490-9000) at
www.MyBacharach.com
for addi-
tional instruction for proper operation.
Refer to the
User Manual (part number
6490-
9000)
at www.MyBacharach.com for detailed
instructions on accessing the internal components
for wiring.
24VAC
L N
24VDC
+ GND
OUT
GND +
RS485
B A
SH
RELAY
NC C NO
1 2 3 4 5 6
7 8 9 10 11 12
2 3 4
9 10
10
Terminal Block
Positions 1-6
Terminal Block
Positions 7-12
24 VAC
NEUTRAL
1 2 3 4 5 6
7 8 9 10 11 12
24VAC
L N
+ GND
OUT
GND +
RS485
B A
SH
RELAY
NC
C NO
24 VDC
24 VDC +
(#3)
24 VDC Ground
(#4)
1 2 3 4 5 6
7 8 9 10 11 12
24VAC
L N
+ GND
OUT
GND +
RS485
B A
SH
RELAY
NC
C NO
24 VDC
WARNING: Incorrect wiring may
permanently damage the gas detector,
and void the warranty. Double check
all terminations before applying power.
WARNING: The MGS-250 must be
powered by either:
• a suitable UL 60950/CSA certified
power supply that is isolated from line
voltage by double insulation, or
• an appropriately rated UL listed/CSA
Class 2 transformer.
Failure to comply can result in personal
injury or death.
WARNING: Neutral
polarity must be
maintained across
units.
TRANSFORMER
24 VAC
NEUTRAL
120 VAC
SUPPLY
24
VAC
NEUTRAL
24
VAC
NEUTRAL
24
VAC
NEUTRAL
Analog Output
Ground (#5)
Analog Output
Signal (+) (#6)
1 2 3 4 5 6
7 8 9 10 11 12
24VAC
L N
+ GND
OUT
GND +
RS485
B A
SH
RELAY
NC
C NO
24VDC
Use 18 to
20 AWG wire
NC (#10)
NO (#12)
COM (#11)
1 2 3 4 5 6
7 8 9 10 11 12
24VAC
L N
+ GND
OUT
GND +
RS485
B A
SH
RELAY
NC
C NO
24VDC
POWER (AC)
POWER (DC)
ANALOG OUTPUT
ALARM OUTPUT
RS-485 “B”
Inverted (#7)
RS-485 “A”
Non-inverted (#8)
Shield (#9)
1 2 3 4 5 6
7 8 9 10 11 12
24VAC
L N
+ GND
OUT
GND +
RS485
B A
SH
RELAY
NC
C NO
24VDC
MODBUS NETWORK
IMPORTANT: For Modbus network
communications wiring, use only 18-24
AWG shielded twisted pair wire with
120 ohm characteristic impedance.
Refrigeration or
Building
Controller
Terminator: IN
RS-485 TERMINATOR
OUT
IN
OUT
IN
OUT
IN
OUT
IN
OUT
IN
OUT
OUT
OUT
IN
IMPORTANT: Be sure to enable the
termination resistor on the device at
each end of the network.