Module Integration Manual
Page 6 of 18
Interrogator RF Board (400.00152.xxxx)
3
I
NTRODUCTION
The INTERROGATOR RF BOARD is a complete interrogation module for passive SAW
sensors. It incorporates four switch-selectable sensor radio signal ports, an interrogation ASIC,
a digital signal processor, and a communications/protocol interface. The module has two serial
data ports (diagnostic port and SCADA port) and an “I
2
C”
[1]
port for attaching wired humidity
sensors.
The INTERROGATOR RF BOARD communications/protocol interface firmware provides high
level measurement commands and also supports MODBUS protocol. This communications and
interface module does not control critical timing related to compliance. Firmware documentation
is available on the relevant commands. A C# DLL is also available for creating PC based
applications.
Figure 1 shows one side of the INTERROGATOR RF BOARD without shielding. The blue outline encloses the
optional Class A partial discharge (PD) receiver. The red outline encloses the Class B RF transceiver circuitry. The
remainder of the circuitry incorporates an integrated Class B digital device. Connectors at lower left and lower center
are programming headers not used in normal operation and optionally unpopulated. The large header at the right is
the host interface.
1
The port is electrically I
2
C but uses a modified protocol of the specific sensor.
SMA1
SMA4
CASE
Earth
stud
SMA3
SMA2
