Microtel CellStat v.1.22 - Manual (Page 14)

MICROTEL CellStat
TM
12
Step Four - Connect External Input/Output to the Dialer Each Fault input
has a corresponding terminal (1 - 4), and there are two COM terminals. See Figure 4
below. The terminals are large enough to accept two 14 AWG wires, so if more than two
faults are wired, the COM terminals must be shared. The fault sensing circuitry is
transformer and optically isolated from the dialer circuitry, but all faults share the same
COM. Use 22 AWG shielded twisted pair wire when wiring external sensors to the I/O
terminals. Whenever possible, ground the shield at the sensor end only. Sensor control
wires should never share conduit with AC power wiring.
The local alarm contacts are normally energized, and closed. When a user-defined alarm
condition exists these contacts are opened (de-energized). These contacts may be used to
drive a low power (10 volt-amps Max.) resistive load, or as a signal to another piece of
process-monitoring equipment. High power and/or inductive loads must be driven from
an external power relay. The local alarm contacts are suitable for driving a 12 – 48 volt
DC relay coil.
NOTE: Keep I/O runs to a maximum length of 150 ft.
Figure 4. I/O Terminal Connections