B&K Precision 4034 - Manual - Manual (Page 41)

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A Program Message Unit having a colon as its first character causes the reference to return to the root.
This process is defined by IEEE 488, section A.1.1. Consider the following examples:
1. The following command may be used to set the high and low levels of the pulse. Note that the
LOW command is referenced to the command preceding it. The LOW mnemonic resides at the
same node as the HIGH command.
SOURCE:VOLTAGE:HIGH 5V;LOW 2V
2. This command sets the frequency and the high level. The FREQUENCY and VOLTAGE
mnemonics are at the same level.
SOURCE:FREQUENCY 2KHZ;VOLTAGE:HIGH 4V
3. When Program Message Units describe different subsystems, a colon prefix must be used to
reset the command reference to the root. Here the frequency and the output state are set.
SOURCE:FREQUENCY 3KHZ;:OUTPUT:STATE ON
Common Commands may be inserted in the Program Message without affecting the instrument-
control command reference. For example,
SOURCE:VOLTAGE:HIGH 4V;*ESE 255;LOW 2V
4.10 Status Reporting
The instrument is capable of reporting status events and errors to the controller, using the IEEE 488.1
Service Request function and the IEEE 488.2 Status Reporting structure.
4.10.1 The Status Byte
Status summary information is communicated from the device to the controller using the Status Byte
(STB). The STB is composed of single-bit summary-messages, each summary message summarizing
an overlying Status Data Structure. By examining the content of the STB, the controller gains some
information concerning the instrument's status. The STB bits are defined as follows:
Bit 0: Unused
Bit 1: Unused
Bit 2: Error/event queue summary message (EVQ). This bit is set if the queue is not empty.
Bit 3: Questionable Status summary message. This bit is not used by the pulse generator.
Bit 4: Message Available (MAV) summary message. This bit is set whenever all or part of a
message is available for the controller to read. The controller may be ready to read the
response message before it is available, in which case it can either wait until this bit is
set, or it can start to read. In the second case, the controller time-out must be set so that
the read action will not be aborted before the message has been read.
Bit 5: Event Status Bit (ESB) summary message. This bit is set to indicate that one or more of
the enabled standard events have occurred.
Bit 6: Request Service (RQS). This bit is set when the device is actively requesting service.
Bit 7: Operation Status summary message. No Operation Status events are defined in the pulse
generator, and so this bit is never set.
The STB is read by the controller during a serial poll. If the RQS bit was set, it is then cleared. The
STB may also be read by the *STB? common query.
4.10.2 Service Request Enabling
Service request enabling allows the user to select which Status Byte summary messages may cause the
device to actively request service. This is achieved using the Service Request Enable Register, which