IEC/IEEE Bus Interface

The standard instrument is equipped with a GPIB bus (IEC/IEEE bus) connection. The two interface connectors labeled IEC BUS and IEC SYSTEM BUS are located on the rear panel of the instrument.

Always use a shielded cable to connect the GPIB bus interfaces.

Characteristics of the interface

  • 8-it parallel data transfer

  • Bidirectional data transfer

  • Three-line handshake

  • High data transfer rate of max. 1 MByte/s check ZVAB

  • Up to 15 devices can be connected

  • 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.

  • Wired OR if several instruments are connected in parallel

Pin assignment

Bus lines

1. Data bus with 8 lines D0 to D7The transmission is bit-parallel and byte-serial in the ASCII/ISO code. D0 is the least significant bit, D7 the most significant bit.

2. 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:
ATN=HIGH active LOW marks the end of data transmission.
ATN=LOW active LOW triggers a parallel poll.

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 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 analyzer provides the following functions to communicate via GPIB bus:

Interface Functions

Instruments which can be controlled via GPIB bus can be equipped with different interface functions. The interface function for the network analyzer are listed in the following table.

Control character

Interface function

SH1

Handshake source function (source handshake), full capability

AH1

Handshake sink function (acceptor handshake), full capability

L4

Listener function, full capability, de-addressed by MTA.

T6

Talker function, full capability, ability to respond to serial poll, deaddressed by MLA

SR1

Service request function (Service Request), full capability

PP1

Parallel poll function, full capability

RL1

Remote/Local switch over function, full capability

DC1

Reset function (Device Clear), full capability

DT1

Trigger function (Device Trigger), full capability

Interface Messages

Interface messages are transmitted to the instrument on the data lines, with the attention line being active (LOW). They serve to communicate between controller and instrument.

Universal Commands

Universal commands are encoded in the range 10 through 1F hex. They are effective for all instruments connected to the bus without pervious addressing.

Command

QuickBASIC command

Effect on the instrument

DCL
(Device Clear)

IBCMD (controller%, CHR$(20))

Aborts the processing of the commands just received and sets the command processing software to a defined initial state. Does not change the instrument settings.

IFC
(Interface Clear)

IBSIC (controller%)

Resets the interfaces to the default setting.

LLO
(Local Lockout)

IBCMD (controller%, CHR$(17))

The LOC/IEC ADDR key is disabled.

SPE
(Serial Poll Enable)

IBCMD (controller%, CHR$(24))

Ready for serial poll.

SPD
(Serial Poll Disable)

IBCMD (controller%, CHR$(25))

End of serial poll.

PPU 
(Parallel Poll Unconfigure)

IBCMD (controller%, CHR$(21))

End of the parallel-poll state.

 

Addressed Commands

Addressed commands are encoded in the range 00 through 0F hex. They are only effective for instruments addressed as listeners.

Command

QuickBASIC command

Effect on the instrument

GET
(Group Execute Trigger)

IBTRG (device%)

Triggers a previously active device function (e.g. a sweep). The effect of the command is the same as with that of a pulse at the external trigger signal input.

GTL
(Go to Local)

IBLOC (device%)

Transition to the "Local" state (manual control).

PPC
(Parallel Poll Configure)

IBPPC (device%, data%)

Configures the instrument for parallel poll. Additionally, the QuickBASIC command executes PPE/PPD.

SDC
(Selected Device Clear)

IBCLR (device%)

Aborts the processing of the commands just received and sets the command processing software to a defined initial state. Does not change the instrument setting.

 

Instrument Messages

Instrument messages (commands) are transferred on the data lines of the GPIB bus while the ATN line is not active. ASCII code is used.

Structure and syntax of the instrument messages are described the SCPI Reference chapter. The chapter also provides a detailed description of all messages implemented by the analyzers.