General Bus Management Lines - HP 8711C User Manual

Front/Rear Panel
Connectors
As many as 14 HP-h3 instruments can be connected to the analyzer
(15 total instruments in the system). The cables can be interconnected in
a star pattern (one central instrument with the HP-IB cables emanating
from that instrument like spokes on a wheel), or in a linear pattern (like
boxcars on a tram), or a combination of the two. See Figure l-5 in Chapter 1.
There are certain restrictions that must be followed when interconnecting
instruments:
Each instrument must have a unique HP-IB address, ranging from 0 to 30.
l
In a two-instrument system that uses just one HP-IB cable, the cable length
l
must not exceed 4 meters (13.2 ft).
When more than two instruments are connected on the bus, the cable
l
length to each instrument must not exceed two meters (6.6 ft).
The total cable length between all instruments must not exceed 20 meters
l
(66 ft).
Hewlett-Packard manufactures HP-IB extender instruments (Models
HP 37204A) and HP 37204B) that overcome the range limitations imposed by
the cabling rules. These extenders allow twin pair cable operation up to 1 km
(3,280 ft), and telephone modem operation over any distance. HP Sales and
Service Offices can provide additional information on the HP-IB extenders.
Name
Attention
Interface Clear
Service Request
Remote Enable
End Or Identify
8-8
深圳市盛腾仪器仪表有限公司
Table 8-l. General Bus Management lines
Mnemonic
Controls whether the bus is in Command Mode lATN TRUE1 or Data Mode
ATN
Initializes the interface to en idle state lno activity on the bus).
Alerts the Controller to a need for communication.
REN Enables devices to respond to Remote Program Control when addressed
to listen.
Indicates last data byte of a multibyte sequence; also used with ATN to parallel
EOI
poll devices for their status bit.
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