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GMC-I Gossen-Metrawatt GmbH
6
Operating Commands
Nearly all of the functions of the SSP KONSTANTER can be
remote controlled via the IEEE 488 interface (= IEC 625), or the
RS 232C interface.
With the exception of a few functions specific to the IEC bus, all
device settings and device responses are triggered with character
strings which are transmitted in ASCII code. Transmission of
device messages is accomplished as follows:
•
Byte-serial via the IEC bus with a specific 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 this device.
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.
All commands used to query device settings or measured values
are identified with a question mark (?) at the end. Thus the query
command:
USET?
is used to determine the presently selected voltage value.
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 which can be abbreviated are identified through the
use of mixed typefaces. The portion of the command which does
not appear in boldface can be left out. However, the question
mark (?) must always be transmitted with query commands.
Example 1:
The following abbreviations can be used for the “OUTPUT” setting
command:
OU
TPUT
OU
TPU
OU
TP
OU
T
OU
Example 2:
The following abbreviations can be used for the “DELAY?” query
command:
DE
LAY
?
DE
LA
?
DE
L
?
DE?
Query Commands
All query commands are identified with a question mark (?) at the
end. The device makes a response available to the control
computer in response to query commands. 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 (16 decimal) is set in
the status byte register (MAV: message available).
Text Parameters
Text parameters are parameters which begin with a letter.
Selection can be made from a group of text parameters for all
commands which use text parameters.
Example:
DISPLAY ON
DISPLAY OFF
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 can have up to two places, and the entire
parameter may not exceed a length 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, and the leading plus sign can be left out. If several
parameters are included they are separated by commas (,), and a
blank can be entered before and after each parameter as well.
Example:
Parameter to be entered: 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
h
) 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.
Stringing Commands Together
Several commands can be strung together in a row and
transmitted as a command string. If several parameters are
included they are separated by semicolons (;), and a blank can be
entered before and after each semicolon as well.
Example:
USET 10; OUTPUT ON; IOUT?
Comment
The individual commands are executed in the order they were
received.
Setting and query commands can be mixed in a single command
string.
If a string contains several query commands, semicolons (;) are
inserted between the requested parameters in the response
string as well.
If a string contains a faulty command, the respective command is
ignored, and the corresponding error bit is set in the event
standard register (ESR), but all remaining commands are
nevertheless executed.