HP E1326B User Manual page 32

Analog Bus
Connections at the
Multimeter
Digital Bus Overview
Chapter 2
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The analog bus coming from the multiplexer consists of six lines. On the
multiplexer terminal block these lines are labeled:
H L G I+ I- IG
Where the ribbon cable connects the multiplexer to the multimeter the lines
are labeled:
H L G H L G
The lines are then connected to the multimeter's HI LO COM HI lines as
shown in Figure 2-9.
Figure 2-9. Analog Bus Connections
The digital bus cable coordinates the operation (handshaking) between the
multimeter and FET multiplexers without involvement from the system
instrument. This enables the multimeter to scan the FET channels at a rate
of approximately 13,150 channels/sec.
The digital bus consists of a Voltmeter Complete line, an (external) Trigger
line, and ground. The handshake sequence is described in the following
steps and in Figure 2-10.
1. When a FET channel is closed, a "channel closed" signal is sent over
the Trigger line. This triggers the multimeter which, in turn, makes a
measurement.
2. When the measurement is finished, a "voltmeter complete" signal is
sent from the multimeter to the multiplexer on the Voltmeter
Complete line. This signal advances the scan to the next channel in
the list. When the channel is closed, the channel closed signal
triggers the multimeter and the process repeats.
Figure 2-10. Digital Bus Overview
Configuring the HP E1326B/E1411B Multimeter 31