Sensoray 7429 - Manual (Page 6)

INTRODUCTION
F UNCTIONAL D ESCRIPTION
The 7429 interfaces sixteen process sensors directly to the STD bus. Each of the sixteen
sensor channels may be independently configured via software to accept thermocouple,
RTD, strain gage, thermistor, current loop, or DC voltage inputs.
Pulsed sensor excitation is provided for thermistors, RTD's, and strain gages in order to
minimize self-heating effects. Cold junction compensation is provided for thermocou-
ples on the optional 7409TB sensor screw termination boards, and all inputs are pro-
tected from high common mode voltages.
The 7429's onboard microprocessor continuously scans through the sixteen channels.
As each channel is scanned, the channel sensor signal is digitized, linearized, and con-
verted to engineering units appropriate for the sensor type. The most recent sensor data
from each channel is immediately accessible to the host processor.
Communication with the host processor is achieved via two contiguous I/O ports which
may be mapped anywhere in the STD bus I/O address space. Communication interrupts
are provided to support the demands of high performance real time systems. Interrupts
may be routed onto the STD bus INTRQ* line or directly to an external interrupt con-
troller for more complex interrupt-driven systems.
S PECIFICATIONS
Electrical
Input power ±12.0 to ±15 VDC, ±35 mA
+5.0 VDC, 100 mA
Operating temperature range -25°C to 85°C for specified accuracy
CMRR 80dB minimum
A/D converter 16-bit integrating