DESCRIPTION:
The WTM1 Weatherproof Temperature Monitor, developed by Bradshaw Communication
Systems, is a serial interfaced temperature monitoring unit providing both local ambient
temperature monitoring as well as remote temperature monitoring capability via optional
remote temperature sensors. The base unit is supplied with a built in local temperature probe
which measures temperature at the unit. As few as one and a many as sixteen additional
temperature sensor/s can optionally be added to provide additional remote monitoring.
The WTM1 is housed in an IP66/NEMA 4X enclosure, thus supporting the most rugged
outdoor applications. The WTM1 is provided with one factory installed watertight cable entry
gland to support the interface cable. Each optional remote temperature sensor is provided
with it’s own supporting cable gland. Up to four additional cable glands can be supported by
the base unit by means of existing knockout holes. Since the optional temperature sensors
are connected in a parallel 3-wire buss configuration, additional sensors in excess of four will
require external user supplied terminations by means of two primary host cables routed from
the WTM1. All optional temperature sensors are connected to two separate connectors (Bank
1 & Bank 2), each capable of supporting up to eight sensors each. Rubber ‘build up” tape is
provided with both the WTM1 and with each optional temperature sensor to support round and
irregular cable outside diameters down to 0.10 inch. WTM1 electrical terminations are
provided via internal screw type pluggable terminal blocks, providing fast, easy, and accurate
termination of interface wiring.
Each digital temperature sensor has a unique 64-bit serial number stored onboard and this
serial number is permanently marked on the exterior of each temperature sensor. This allows
each sensor to be identified individually while on the parallel 3-wire buss.
With a temperature measurement range of -55
°
C to +125
°
C and an accuracy of 0.5
°
C from -
10
°
C to +85
°
C on each temperature sensor, the WTM1 provides great flexibility for use in
many applications. Temperature sensor resolution is provided in 0.0625
°
C increments.
The WTM1 serial data is sent (unsolicited) as a “readable” hexadecimal data frame for each
sensor. Each frame consists of a fixed start byte, 8 bytes containing the serial number for a
given sensor, and finally 9 bytes containing the temperature data and CRC. Each
temperature sensor is polled by the WTM1 and its data frame transmitted consecutively until
all connected temperature sensors have been polled, then an approximate 5-second delay will
occur until the start of the next polling/transmission cycle. This cycle then continues as long
as power is supplied to the WTM1. The serial output of the WTM1 is compliant with ANSI
Standards TIA/EIA-422-B and TIA/EIA-485-A.
Refer to the WTM1 Serial Interface Protocol Document for further definition of the WTM1 serial
output.
Visual monitoring of functionality is provided on the main board by means of two LED
indicators. One indicating the WTM1 is operating and the second indicating the WTM1 is
polling temperature sensor/s.
INSTALLATION:
Mount the WTM1 in an easily accessible location. 8-32 Socket Head Cap Screws and
associated hardware are normally used to secure the WTM1 to a mounting bracket or similar.
Refer to the WTM1 Outline Mounting Drawing (provided separately) for mounting dimensions
and verify the WTM1 is securely mounted. Open the cover to the WTM1. Install the interface
cable through the WTM1 cable gland. Use the supplied cable “build-up” tape for cable O.D.s
under 0.23 inches to ensure a watertight seal. Electrically connect WTM1 TB1 per the WTM1
Installation Figure & WTM1 Termination Table below. TB2 and TB3 may also be terminated at
this time if optional remote temperature sensors were purchased. Multiple wires may be
installed in each terminal depending upon wire gauge used. If more than four optional remote
sensors are implemented, the user will need to provide an additional junction box and wire
connectors to allow the full complement of 16 optional remote sensors to be utilized.
Once the terminations are complete, apply power, and check for the DS1 Micro Run LED to
flash at a rate of about once per second. This indicates the microprocessor is running. Each
time a sensor is polled and it’s data transmitted, the DS2 Sensor Read LED will flash. The
WTM1 should now be functioning correctly. As long as power is supplied to the WTM1, it will
continuously poll the built in temperature sensor as well as any additional remote sensors and
continuously transmit each sensor’s temperature data over the RS422 serial output. Make
note of the WTM1 local sensor serial number on the label inside the cover and/or on each
remote sensor. Refer to the WTM1 Serial Interface Protocol Document for protocol definition.
Close the cover securely to ensure a watertight seal (DO NOT OVERTIGHTEN COVER
SCREWS OR ENCLOSURE DAMAGE WILL RESULT!).
WTM1 TERMINATION TABLE
TB1 1
2
3
4
FU9-24VDC Return
(GND) RS422 TD(A)/TX(-)
RS422 TD(B)/TX(+)
TB2 & TB3
1
2
3
FUNCTION
Remote 5V
Remote Sensor Data
Remote Sensor Gnd.
WIRE COLOR
RED
BLUE (or BLACK)
SHIELD (or DRAIN)
1 2 3
1
3
2
1 2 3 4
+9
-24 V
.D
.C
RET
URN (
G
RO
UND)
R
S
4
22
TD
(A)
/ TX (-)
RS
42
2 T
D
(
B
) /
T
X
(
+
)
GN
D
/ S
H
IE
LD
(DR
A
IN
)
DAT
A
/ BLUE
(B
LACK
)
+5
V
/
R
E
D
OP
T
IONA
L
REM
O
T
E
SEN
S
O
R #
9
OP
T
IONA
L
REM
O
T
E
SEN
S
O
R #
1
0
DAT
A
/ BLUE
(B
LACK
)
GN
D
/ S
H
IE
LD
(DR
A
IN
)
+5
V
/
R
E
D
OP
T
IONA
L
REM
O
T
E
SEN
S
O
R #
1
1
DAT
A
/ BLUE
(B
LACK
)
GN
D
/ S
H
IE
LD
(DR
A
IN
)
+5
V
/
R
E
D
OP
T
IONA
L
REM
O
T
E
SEN
S
O
R #
1
2
DAT
A
/ BLUE
(B
LACK
)
GN
D
/ S
H
IE
LD
(DR
A
IN
)
+5
V
/
R
E
D
OP
T
IONA
L
REM
O
T
E
SEN
S
O
R #
1
3
DAT
A
/ BLUE
(B
LACK
)
GN
D
/ S
H
IE
LD
(DR
A
IN
)
+5
V
/
R
E
D
OP
T
IONA
L
REM
O
T
E
SEN
S
O
R #
1
4
DAT
A
/ BLUE
(B
LACK
)
GN
D
/ S
H
IE
LD
(DR
A
IN
)
+5
V
/
R
E
D
OP
T
IONA
L
REM
O
T
E
SEN
S
O
R #
1
5
DAT
A
/ BLUE
(B
LACK
)
GN
D
/ S
H
IE
LD
(DR
A
IN
)
+5
V
/
R
E
D
OP
T
IONA
L
REM
O
T
E
SEN
S
O
R #
1
6
DAT
A
/ BLUE
(B
LACK
)
GN
D
/ S
H
IE
LD
(DR
A
IN
)
+5
V
/
R
E
D
OP
T
IONA
L
REM
O
T
E
SEN
S
O
R #
8
OP
T
IONA
L
REM
O
T
E
SEN
S
O
R #
1
OP
T
IONA
L
REM
O
T
E
SEN
S
O
R #
2
OP
T
IONA
L
REM
O
T
E
SEN
S
O
R #
3
OP
T
IONA
L
REM
O
T
E
SEN
S
O
R #
4
OP
T
IONA
L
REM
O
T
E
SEN
S
O
R #
5
OP
T
IONA
L
REM
O
T
E
SEN
S
O
R #
6
OP
T
IONA
L
REM
O
T
E
SEN
S
O
R #
7
DAT
A
/ BLUE
(B
LACK
)
+5
V
/
R
E
D
GN
D
/ S
H
IE
LD
(DR
A
IN
)
GN
D
/ S
H
IE
LD
(DR
A
IN
)
DAT
A
/ BLUE
(B
LACK
)
+5
V
/
R
E
D
GN
D
/ S
H
IE
LD
(DR
A
IN
)
DAT
A
/ BLUE
(B
LACK
)
+5
V
/
R
E
D
GN
D
/ S
H
IE
LD
(DR
A
IN
)
DAT
A
/ BLUE
(B
LACK
)
+5
V
/
R
E
D
GN
D
/ S
H
IE
LD
(DR
A
IN
)
DAT
A
/ BLUE
(B
LACK
)
+5
V
/
R
E
D
GN
D
/ S
H
IE
LD
(DR
A
IN
)
DAT
A
/ BLUE
(B
LACK
)
+5
V
/
R
E
D
GN
D
/ S
H
IE
LD
(DR
A
IN
)
DAT
A
/ BLUE
(B
LACK
)
+5
V
/
R
E
D
GN
D
/ S
H
IE
LD
(DR
A
IN
)
DAT
A
/ BLUE
(B
LACK
)
+5
V
/
R
E
D
BASE UNIT TEMPERATURE SENSOR
INTERFACE CABLE
(CUSTOMER SUPPLIED)
