Tettex MIDAS 2881, Operating Instructions Manual

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80 Software
<NR3> Real numbers with exponents 1.56E+1, -1.67E-12
<String> Character sequences without CTRL
(ASCII 13) and LF (ASCII 10) (see also
the “Command Syntax” section). 'Test character sequence'
<ARBITRARY ASCII
RESPONSE DATA> Character sequences of indefinite length,
closed by the end character. abcdefg.......z and even
more<EOS>
<DEFINITE LENGTH
ARBITRARY BLOCK
RESPONSE DATA> Data byte sequence with definite length,
closed by the end character #10 0123456789<EOS>
Register
Various registers are used in MIDAS in order to interrogate the state of the device via the interface.
Most registers are defined in the IEEE 488.2 Standard and are extended for the specific
characteristics of the MIDAS. The following table shows the relationship of all registers used together
with the associated bit assignments and resulting values:
*STB
Status Byte
Register
Bit
7
Not in use, always '0'
6 RQS/MSS (Status of the RQS line) if queried over the serial connection
MSS (Master Summary Status) if queried via the *STB?
'1', if a message exists for the controller.
5 ESB (Standard Event Status Bit). Set, if since the last read or delete operation
something has changed in the Event Status Register.
4 MAV (Message Available). Set if there is still data to read through the
controller.
3 Not in use, always '0'
2 Not in use, always '0'
1 Not in use, always '0'
0 ISR. Set if the internal status register has a changed contents. The internal
status can be queried with ISR?
*SRE
Service
Request
Enabling
Register
Used to mask the status byte bits (with the exception of bit 6). If a bit is set to '1' in
this register, then the associated bit in the status register can be set as a collective
alarm and initiate a request, otherwise nothing will happen.
*ESR
Standard Event
Status Register
Bit
15 - 8 Reserved— answer with '0'
7
PON Set to '1' when the MIDAS is switched on
6 URQ Not used
5 CME Shows the processing errors that are stored in the CMR register
and can be queried with CMR?
4 EXE Shows a execution error that is stored in the EXR register and
can be queried with EXR?
3 DDE Shows that a MIDAS-specific error has occurred and which can
be queried with DDR?
2 QYE Shows a query error that is stored in the QYR register and can be
queried with QYR?
1 RQC Always '0' because the MIDAS is not able to take over bus
control.
0 OPC Unused and always '1' if and *OPC is recognised because all
commands are processed in a strictly one after another.