Associated Research 7700, Руководство по эксплуатации и обслуживанию

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EOI (end or identify) This line has two purposes- the Talker uses this line to mark the
end of a message string, and the Controller uses it to tell devices to identify their response
in a parallel poll.
8.5. GPIB Connector
Connection is usually accomplished with a 24-conductor cable with a plug on one end
and a connector at the other end. Devices may be connected in a linear, star or a
combination configuration.
The standard connector is the Amphenol or Cinch Series 57 Microribbon or AMP
CHAMP type. The GPIB uses negative logic with standard transistor-transistor logic
(TTL) levels. When DAV is true, for example, it is a TTL low level (

0/8 V), and when
DAV is false, it is a TTL high level (

2.0 V).
Restrictions and Limitations on the GPIB
A maximum separation of 4 m between any two devices and an average separation of 2 m
over the entire bus.
A maximum total cable length of 20 m.
No more than 15 device loads connected to each bus, with no less than two-thirds
powered on.
Note: A bus extender which is available from numerous manufacturers is available to
overcome these limitations.
8.6. Interface Functions
The capability of a device connected to the bus is specified by its interface functions.
These functions provide the means for a device to receive, process, and send messages
over the bus. The interface functions are listed in the chart below. All functions may be
controlled over the bus except input voltage which is Selectable on the rear panel.
GPIB INTERFACE FUNCTIONS
IEEE-488 INTERFACE Complete handshake capability
Talker/Listener functions
Service request capability
No remote/local capability
No parallel poll capability
No device clear capability
No device trigger capability
No controller capability
3 state driver
CONTROLLABLE ITEMS Test/Reset control
Setting of test status/parameters for test