Annexes
R&S
®
ZNB/ZNBT
1255
User Manual 1173.9163.02 ─ 38
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Bidirectional data transfer
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Three-line handshake
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High data transfer rate of max. 1 MByte/s
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Up to 15 devices can be connected
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Maximum length of the connecting cables 15 m. The length of a single connecting
cable should not exceed 2 m, if many devices are used, it should not exceed 1 m.
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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 connec-
ted to the default setting.
ATN
(Attention): active LOW signals the transmission of interface messages, inac-
tive HIGH signals the transmission of device messages.
SRQ
(Service Request): active LOW enables the connected device to send a ser-
vice 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 devi-
ces is not ready for data transfer.
Interfaces and Connectors
