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PSI BOX Reference
devices. Within this limit, the IEEE bus is capable of a
maximum data transfer rate of 250K bytes per second with open
collector drivers, or 500K bytes per second with tri-state drivers.
When shorter distances are involved, 15 metres, with every
device turned on, with not more than 1 device per metre of
cable and with tri-state drivers the maximum theoretical data rate
is 1 Megabyte per second.
Of course, the data is actually transmitted at the speed of
the SLOWEST currently addressed listener or talker. The
positive 3 wire handshake ensures that data is transmitted
correctly and without loss despite the actual speed in use.
____________________ _
Types Of IEEE Devices.
Every device on the IEEE bus must be capable of
acting in at least one of following three roles.
1)
A device acting as a LISTENER.
2)
A device acting as a TALKER.
3)
A device acting as a CONTROLLER.
___________ _
The Listener.
A listener is a device with the capability to receive data
from the IEEE bus when addressed. This transmitted data is
known as device dependant messages.
A typical listener is a printer. Other listeners include disk
drives,
programmable
generators, programmable power supplies etc. There can be up to
14 active listeners simultaneously on the IEEE bus.
The Talker.
__________ _
A talker is a device with the capability to transmit data
over the IEEE bus when addressed. This transmitted data is
known as device dependant messages.
Page 16
__________________ _
Using The IEEE Bus.
oscilloscopes,
IEEE 488 Introduction
programmable
Chapter 2
signal
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