Annexes
R&S
®
ZNC
740
User Manual 1173.9557.02 ─ 13
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Wired OR if several instruments are connected in parallel
Pin assignment
Bus lines
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Data bus with 8 lines D0 to D7:
The transmission is bit-parallel and byte-serial in the ASCII/ISO code. D0 is the least
significant bit, D7 the most significant bit.
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Control bus with five lines:
IFC
(Interface Clear): active LOW resets the interfaces of the instruments connected
to the default setting.
ATN
(Attention): active LOW signals the transmission of interface messages, inactive
HIGH signals the transmission of device messages.
SRQ
(Service Request): active LOW enables the connected device to send a service
request to the controller.
REN
(Remote Enable): active LOW permits switchover to remote control.
EOI
(End or Identify): has two functions in connection with ATN:
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ATN=HIGH active LOW marks the end of data transmission.
–
ATN=LOW active LOW triggers a parallel poll.
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Handshake bus with three lines:
DAV
(Data Valid): active LOW signals a valid data byte on the data bus.
NRFD
(Not Ready For Data): active LOW signals that one of the connected devices
is not ready for data transfer.
NDAC
(Not Data Accepted): active LOW signals that the instrument connected is
accepting the data on the data bus.
The R&S ZNC provides several functions to communicate via GPIB bus. They are descri-
bed in the following sections.
Interfaces and Connectors
