orbit controls OCM191 Betriebsanleitung Seite 48

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STB Status Byte Register
The summary messages from the Event Status Register and Output Queue are used to set or clear
the appropriate bits (B4 and B5) of the Status Byte Register. These bits do not latch, and their states
(0 or 1) are solely dependent on the summary messages (0 or 1). For example, if the Standard Event
Register is read, its register will clear. As a result, its summary message will reset to 0, which in turn
will clear the ESB bit in the Status Byte Register.
Bit configuration of Status Byte Register :
RQS Request Service, bit 6. The RQS bit is set to 1 whenever bits ESB or MAV change from 0 to 1
and are enabled (1) in the SRE. When RQS is 1, the OCM191 asserts the SRQ control line on
the IEEE-488 interface. You can do a serial poll to read this bit to see if the OCM191 is the
source of an SRQ.
MSS Master Summary Status, bit 6. The MSS bit is set to 1 whenever bits ESB or MAV are 1 and
enabled (1) in the SRE. This bit can be read using the *STB? command in the serial remote
control in place of doing a serial poll.
ESB Event Summary Bit, bit 5. The ESB bit is set to 1 when one or more enabled ESR bits are set
to 1. Conversely, the ESB bit is set to 0 when no enabled ESR bits are set to 1.
MAV Message Available, bit 4. The MAV bit is set to 1 whenever data is available in the OCM191
IEEE488 Output Queue. This message is used to synchronize information exchange with the
controller. The controller can, for example, send a query command to the OCM191 and then
wait for MAV to become TRUE. The IEC 625-1 bus is available for other use while an
application program is waiting for a device to respond. If an application program begins a read
operation of the Output Queue without first checking for MAV, all system bus activity is held up
until the OCM191 responds.
SRE Service Request Enable Register
The Service Request Enable Register is an 8-bit register that enables corresponding summary
messages in the Status Byte Register. Thus the application programmer can select reason for a
device (OCM191) to issue a service request by altering the contents of the SRE. The Service Request
Enable Register is read with the *SRE? common query. The response message to this query
represents the sum of the binary-weighted values of the SRE. The value of unused bit 6 shall always
be zero. The Service Request Enable Register is written with the *SRE common command followed by
an integer value (0 – 191). Sending the *SRE common command followed by a zero clears the SRE. A
cleared register does not allow status information to generate a rsv local message and thus, no
service request are issued. The Service Request Enable Register is cleared upon power-on.
ESR Event Status Register
The Event Status Register is a two-byte register in which the higher eight bits are always 0, and the
lower eight bits represent various conditions of the OCM191 calibrator. The ESR is cleared when the
power is turned on, and every time it is read.
Bit configuration of Event Status Register :
PON Power On, bit 7. This event bit indicates that an off-to-on transition has occurred in the
device's power supply.
URQ User Request, bit 6. This event bit indicates disconnecting or connecting of any cable adapter
to the auxiliary connector on the front panel.
CME Command Error, bit 5. This event bit indicates that an incorrectly formed command or query
has been detected by the OCM191.
EXE Execution Error, bit 4. This event bit indicates that the received command cannot be executed,
owing to the device state or the command parameter being out of bounds.
Betriebsanleitung
OCM191 Isolation Tester - Kalibrator
48