Agilent 34970A/34972A Data Acquisition / Switch Unit
Agilent 34970A/34972A Data Acquisition / Switch Unit
Agilent 34970A/34972A Data Acquisition / Switch Unit
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Chapter 5 Theory of Operation<br />
Backplane<br />
Backplane<br />
Unless otherwise noted, components in this discussion are located on the<br />
A3 circuit assembly (34970-66503).<br />
The backplane contains three connectors, P101, P102, and P103 for<br />
connection to the plug-in modules. The parallel lines in these connectors<br />
are divided into two groups to form the analog bus and digital bus.<br />
Analog Bus<br />
The analog bus connects the signals from the plug-in modules to the<br />
Internal DMM. There are five lines in the analog bus, HI, LO,<br />
OHMS_HI, OHMS_LO, and AMPS. The HI and LO lines are protected<br />
from overvoltages by E101, E102, RV101, RV102, R101, R160, L101,<br />
L102, and C109.<br />
P105 makes the analog bus connection to the internal DMM.<br />
Digital Bus<br />
The digital bus uses 10 lines for communication and control. P104 makes<br />
the digital bus connection to the earth referenced logic and floating logic.<br />
Signal<br />
P101, P102, P103<br />
Pins<br />
Comments<br />
Slot ID A6, A7, A8 Unique binary code for each slot.<br />
DATA_IN B6 Serial module data from the floating logic.<br />
DATA_OUT C6 Serial module data to the floating logic.<br />
DGND A5, B5, B7, C5, C7 Earth referenced digital ground.<br />
+5 V A3, B3, C3 Earth referenced module power supply.<br />
Earth Ground A1, B1, C1 Earth referenced zap return ground.<br />
RST B8 Module reset from the earth referenced logic.<br />
SRQ C8 Module service request to the earth<br />
referenced logic.<br />
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