R&S SMJ100A, Operating Manual

Page: 456 / 874

Remote Control Basics
R&S
®
SMJ100A
440 Operating Manual 1403.7458.32 ─ 14
at the standardization of device-specific commands, error handling and the status reg-
isters. The tutorial "Automatic Measurement Control - A tutorial on SCPI and IEEE
488.2" from John M. Pieper (R&S order number 0002.3536.00) offers detailed informa-
tion on concepts and definitions of SCPI.
Tables provide a fast overview of the bit assignment in the status registers. The tables
are supplemented by a comprehensive description of the status registers.
6.1.1 VISA Libraries
VISA is a standardized software interface library providing input and output functions to
communicate with instruments. Thus, you can configure the interface without having to
adjust the application program to the used interface. The I/O channel (LAN or TCP/IP,
USB, GPIB,...) is selected at initialization time by means of the channel–specific
address string ("VISA resource string"), or by an appropriately defined VISA alias
(short name). See also
Chapter 6.1, "Remote Control Interfaces and Protocols" ,
on page 439 for an overview.
Instrument access via VXI-11 or HiSLIP protocols is achieved from high level program-
ming platforms using VISA as an intermediate abstraction layer. VISA encapsulates
the low-level VXI or GPIB function calls and thus makes the transport interface trans-
parent for the user.
A VISA installation is a prerequisite for remote control using the following interfaces:
●
LAN Interface using Chapter 6.1.3, "LAN Interface" , on page 441
●
LAN interface using Chapter 6.1.3.2, "VXI-11 Protocol" , on page 443
●
Chapter 6.1.4, "GPIB Interface (IEC/IEEE Bus Interface)" , on page 444
Instrument access via the LAN socket protocol or GPIB connections can be operated
both, with or without the VISA library.
See also Chapter 6.1.3.3, "Socket Communication" , on page 443 and Chapter 6.1.4,
"GPIB Interface (IEC/IEEE Bus Interface)" , on page 444.
For more information about VISA refer to the user documentation.
6.1.2 Messages
The messages transferred on the data lines are divided into the following categories:
●
Interface messages
Interface messages are transmitted to the instrument on the data lines, with the
attention line being active (LOW). They are used to communicate between the con-
troller and the instrument. Interface messages can only be sent by instruments that
have GPIB bus functionality. For details see the sections for the required interface.
●
Instrument messages
Instrument messages are employed in the same way for all interfaces, if not indica-
ted otherwise in the description. Structure and syntax of the instrument messages
are described in
Chapter 6.3, "SCPI Command Structure" , on page 462. A detailed
Remote Control Interfaces and Protocols