User manual

58 GMC-I Gossen-Metrawatt GmbH
6 Operating Commands
• Nearly all of the device functions offered by the SSP KONSTANTER
can be remote controlled via the IEEE 488 interface (= IEC 625),
or the RS 232C interface.
• Device settings and device responses are triggered by character
strings, which are transmitted in ASCII code.
The only exceptions to this rule are several IEC bus-specific
functions.
• Transmission of device messages is accomplished as follows:
– Byte-serial via the IEC bus with the help of a special 3-wire
handshake
– Bit-serial via the RS 232C interface in consideration of selected
operating parameters
• Detailed information regarding the respective data transmission
operating modes can be found in the applicable standards, or in
the interface description included with your controller.
• The layout of device messages complies in general with “Code,
Format, Protocol and General Command Accords” in accordance
with IEEE 488.2 and IEC 625-2.
• Standard commands for programmable instruments (SCPI)
used by some manufacturers do not apply to the
KONSTANTER.
6.1 Syntax
• The commands are named according to the English
designations for the corresponding functions.
• For example, the command:
USET 12
is used to set the output to a voltage value of 12 V.
• Each command consists of a header, and one or more
parameters as required.
• Differentiation is made between numeric parameters and text
parameters.
• Headers and text parameters can be entered either as upper case
or lower case letters, or as a combination of both.
• At least one blank must be entered between the header and the
parameter.
• If several parameters are included they are separated by
commas (,), and a blank can be entered before and after each
parameter as well.
Examples:
OUTPUT ON
Output on
START_STOP 20,110
Abbreviated Commands
• Commands can be abbreviated.
• The greatest possible extent of abbreviation is highlighted for each
command throughout all of chapter 6.
• The portion of the header which is not highlighted can be
omitted.
• Make sure to include question marks (?) in query commands,
even where abbreviations are used.
Example 1:
The following abbreviations can be used for the OUTPUT
setting command:
OUTPUT / OUTPU / OUTP / OUT / OU
Example 2:
The following abbreviations can be used for the DELAY?
query command:
DELAY? / DELA?/ DEL?/ DE?
Query Commands
• Result in querying of a device setting or measured values.
• Query commands always end with a question mark (?).
• The device transmits a response to the control computer.
• If the IEEE 488 interface is used, the status byte can be queried
or serial polling can be initialized in order to determine whether
or not a device message is available.
• If this is the case, bit 4 is set in the status byte register (MAV:
message available).
Example:
USET?
is used to query the voltage setpoint.
Text Parameters
• Text parameters generally begin with a letter.
• Selection can be made from a group of texts for all commands
which use text parameters.
Example:
Command: DISPLAY txt
Range: OFF
ON
• In the example above, DISPLAY is the header, and ON and OFF
are the group of allowable text parameters.
Numeric Parameters
• Numeric parameters can be entered as whole numbers, or as
fixed or floating decimal point numbers with or without exponent.
• The exponent may occupy up to two places.
• The entire parameter may not exceed a length of 30 places.
• An upper or a lower case letter can be used for the exponent
symbol “E”.
• A blank can be entered to the left and to the right of the
exponent symbol.
• Leading plus signs can be omitted.
• If several parameters are included they are separated by
commas.
• Blanks can be entered to the left and to the right of parameters.
Example: 12.5 (twelve + decimal fraction)
12.5 0012.5
1.25E1 +1.25 E+01
1.25e1 1250.0e-2
Commands per IEEE 488.2 with Asterisk
• Standard commands are used for programming device and
interface functions included with the SSP KONSTANTER, which are
described in the IEEE 488.2 (and 625-2) standard.
• These commands are identified with an asterisk (*) (2A
hex
) at
the beginning of the header.
• The asterisk is part of the header and must be transmitted with
the command.
• Please read the applicable sections of the specified standard for
detailed information concerning these commands.