Gossen MetraWatt SSP 120 Series, Operating Instructions Manual

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58 GMC-I Messtechnik 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 OU TPUT
setting command:
OUTPUT / OUTPU / OUTP / OUT / OU
Example 2:
The following abbreviations can be used for the DE LAY ?
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: DI SPLAY 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 ( 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.