KEPCO TMA 4882-27 - Manual (Page 43)

TMA 4882-27 021910
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3.6.8.4 MULTIPLE LOGICAL INSTRUMENTS
The TMA 4882-27 is a SCPI device that supports multiple logical instruments; it allows a choice
between two methods of status reporting. The status reporting default upon powerup treats the
unit as a single channel instrument. When multiple channels are in use, a SCPI compliant status
structure can be selected which provides an INSTrument summary status register and an indi-
vidual instrument ISUMmary for each logical instrument. These registers are equivalent to the
Status Questionable register of a single channel instrument and are also found in the STATus
Questionable register for the selected channel. The contents of the STATus Questionable regis-
ter can also contain the summary of all instruments as shown in Figure 3-5.
The selection of the status reporting structure is controlled by the SYStem:SET SI (Instrument
Structure) command, either SI0 (off) or SI1 (on). The power-up default is the off condition. To
enable the SCPI compliant mode of operation for multiple logical instruments the user must
send SYSTem:SET SI1 to the TMA 4882-27 during initialization. The SI1 state is not remem-
bered when the unit is turned off. To return to the standard method of reporting the selected
device’s status without turning the unit off, send SYSTem:SET SI0.The state of the power
power supply upon power up for language (SCPI/CIIL), compatibility and GPIB addressing is
selected by DIP switches P1 and P2 (see PAR. 2.2.2 and Table 2-2).
When the TMA 4882-27 is set up for SCPI compliant status reporting for multiple channels, the
specific instrument’s Questionable register is found in the STAT:QUES:INST:ISUM<n> register.
This register has the same bit structure as the single channel Questionable register. The ISUM
enable register is ANDed with the bits of the channel’s ISUM register and its bit is placed in the
INST register. The Questionable register bits are the logical OR-ing of all channels’ Question-
able ISUM register. This is shown in figure 3-5.
The ISUMmary registers set the INSTrument register, which in turn sets bit 13 of the QUEStion-
able or OPERation status register. This is shown pictorially in Figure 3-5.
The STATUS:QUESTIONABLE and STATUS:QUESTIONABLE:CONDITION registers are the
same in this mode of status reporting. The condition register indicates the status of the various
event registers and bits set are only cleared if the source of the bit is cleared.