Rohde & Schwarz 1065.6000.20, Operating Manual

Page: 396 / 438

FSE Instrument Interfaces
1065.6016.12 8.3 E-15
Bus Lines
1. Data bus with 8 lines DIO 1 to DIO 8.
The transmission is bit-parallel and byte-serial in the ASCII/ISO code. DIO1 is the least significant,
DIO8 the most significant bit.
2. Control bus with 5 lines.
IFC (Interface Clear),
active low resets the interfaces of the devices 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 a device connected to send a service request to the controller.
REN (Remote Enable),
active low permits the switch over to remote control.
EOI (End or Identify),
has two functions in connection with ATN:
active low marks the end of data transmission when ATN=high
active low triggers a parallel poll when ATN=low.
3. 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 devices connected is not ready for data transfer .
NDAC (Not Data Accepted),
active low as long as the device connected is accepting the data present on the data bus.