Revised 8/14/02 • U253
7
© 2002 Automated Logic Corporation
6. Disconnect the LogiStat Adaptor cable
from the LogiStat’s LogiPort when
finished to allow the U253 to read inputs
from the LogiStat.
Input Wiring
The U253 inputs support the types of signals
listed below. The LogiStat, LogiStat Plus, and
LogiStat Pro sensors are supported through
the module’s LogiStat port. Refer to Table 1
for information about wire length, gauge, and
shielding. Make sure the U253’s power is off
before wiring any inputs or outputs.
• Thermistor: Precon type 2 (10kohm at
77°F). Input voltages should range
between 0.489V and 3.825V for
thermistors.
• 0 to 5VDC: When using 0 to 5VDC
signals, remove the pull up jumpers of
the U253. The pull up jumpers are
located behind the input port. You must
remove the cover to access the pull up
jumpers. The output impedance of a 0
to 5VDC source must not exceed
10kohms. The input impedance of the
U253 is approximately 1Mohm.
• Dry Contact: A 5VDC wetting voltage is
used to detect contact position. This
results in a 0.5mA maximum sense
current when the contacts are closed.
No pulse accumulation inputs are allowed in
U253 FBs, except for the override button on
the LogiStat.
Using the LogiStat
Use Figure 7 and Figure 8 to wire a LogiStat,
LogiStat Plus, or LogiStat Pro to the U253.
Automated Logic Corporation recommends a
specific wire to connect the U253 to the
LogiStat. This 22AWG solid copper wire is
available from Magnum Cable Corporation,
product number A3LOGISTAT.
Figure 6. Using the LogiPort
Gnd
2 4 Vac
G n d
T e m p
S w
LS 5v
U n e t +
U n e t -
U -c o m
O n
O f f
BACnet
U253
9
Rx
6 1
2- Tx out
3- Rx in
5- Gnd
1,6,8- +10Vor floating
Tx
+5V
A P T
5
Exec. 4relay
Isolate Network
ModeSelect
TTL
485
ACCESS
PORT
LogiS tat
Port
Supplemental
Power
+5V dc
LogiStat Adaptor Cable
LogiStat
Access
Port
Mode Select
Switch
EIA-232
Port
Exec 4 Relay
Switch
Table 1. Input Wiring Restrictions
Input
Maximum
Length
Minimum
Gauge
Shielding
Universal
50 feet
15 meters
24AWG
shielded and
grounded to
module’s “-”
or Gnd
terminal
LogiStat
Sensors
100 feet
30 meters
22AWG
unshielded
Figure 7. Connecting the LogiStat to the U253
Strip 1/4 inch off the ends of the wires before
connecting.
LogiStat
1 2 3 4
4
3
2
1
LogiStat
U module
LS5v
Sw
Temp
Gnd
G
n
d
T
x
R
x
Pw
r
