ILX Lightwave FPM-8200, User Manual

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R E M O T E O P E R A T I O N
Basic GPIB Concepts
01_10 FPM-8200
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C H A P T E R
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GPIB Cable Connections
Standard GPIB connectors can be connected together (stacked), allowing you to
configure the system linearly, or in a star configuration.
Figure 3.1 GPIB Cable Connections
The GPIB Connector
The standard GPIB connector consists of 16 signal lines in a 24-pin stackable
connector. The extra pins are used for some twisted-pair wires. There are eight
data input/output (IO) lines, three handshake lines, and five interface
management lines.
Eight data input/output (DIO) lines carry both data (including device dependent
commands) and interface messages. The ATN interface management line
determines whether these lines contain data or interface messages.
Three handshake lines ensure that all data and messages are reliably transferred:
• NRFD (not ready for data) indicates whether a device can receive the next byte of data or
message.
• NDAC (not data accepted) indicates whether a receiving device has accepted a byte of data
or message.
• DAV (data valid) indicates that the signal levels on the data lines are stable and available for
the receiving device(s) to accept.
Five interface management lines control the flow of information:
• ATN (attention) is set by the controller in charge to define the I/O lines for data or interface
messages.
• IFC (interface clear) is set by the system controller to initialize the bus and assert itself as
controller in charge.
• REN (remote enable) is set by the controller to place addressed devices into remote or local
(front panel) control mode.
• SRQ (service request) can be set by any device in the system to request service from the
controller.
Device A Device B Device C Device D
Device A
Device B
Device C
Device D
linear configuration
star configuration