Tektronix MTD200, Руководство пользователя

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Remote Control
5–48
MTD200 MPEG Test Decoder User Manual
Setting commands causes a modification in the data set. Before the data are
entered in the data set, they are verified for compatibility both with the other data
and with the device hardware. If the setting is not possible, an “execution error”
message will be sent to the status reporting system and the setting ignored. After
successful completion of the verification, setting will immediately be performed.
Prior to the hardware setting, the SETTling bit is set in the STATus:OPERation
register (refer to Table 5–9 on page 5–55). The hardware carries out the settings
and as soon as the settled state is reached, the bit is reset. The SETTling bit is
only set if hardware settings take more time than processing by the command
identification. This bit may be used for synchronization of the command
processing.
Queries cause the data-set management to send the desired data to the output
unit.
The status reporting system collects information about the device status and
makes it available to the output unit on request. Structure and function are
described in Status Reporting System on page 5–49.
The output unit collects the information requested by the controller from the data
set management. It processes such information in line with the SCPI rules and
makes it available in the output buffer. The output buffer has a capacity of 1024
characters. If the requested information is longer, it is made available in portions
in a way that is not noticeable to the controller.
All commands are immediately executed. There is no overlapping command
processing. The user therefore can determine the sequence of execution. The
*WAI command has no effect on the sequence of the command execution.
If a longer command line is terminated by one of two commands (*OPC or
*OPC?), the end of the command processing will be signalled to the controller
by a suitably programmed message.
Table 5–6: Synchronization with *OPC and *OPC?
Command Action after hardware setting Programming of controller
*OPC Setting the Operation Complete bits
in the ESR – Setting bit 0 in the ESE
– Setting bit 5 in the SRE
– Waiting for service request (SRQ)
*OPC? Writing a “1” into the buffer amplifier Addressing the device as a talker
An example for command synchronization is given in Program Examples on
page 5–68.
Status Reporting System
Output Unit
Command Sequence and
Command
Synchronization