Technical data

104 Agilent N8211A/N8212A Performance Upconverter Synthetic Instrument Module, 250 kHz to 20 / 40 GHz
4 Programming the Status Register System
When a condition changes and that condition has been enabled, the request service
summary (RQS) bit in the status byte register is set. In order for the controller to respond to
the change, the Service Request Enable Register needs to be enabled for the bit(s) that will
trigger the SRQ.
Generating a Service Request
The Service Request Enable Register lets you choose the bits in the Status Byte Register
that will trigger a service request. Send the *SRE <num> command where <num> is the
sum of the decimal values of the bits you want to enable.
For example, to enable bit 7 on the Status Byte Register (so that whenever the Standard
Operation Status register summary bit is set to 1, a service request is generated) send the
command *SRE 128. Refer to Figure 6 on page 99 and Figure 7 on page 100 for bit positions
and values.
The query command *SRE? returns the decimal value of the sum of the bits previously
enabled with the *SRE <num> command.
To query the Status Byte Register, send the command *STB?. The response will be the
decimal sum of the bits which are set to 1. For example, if bit 7 and bit 3 are set, the decimal
sum will be 136 (bit 7 = 128 and bit 3 = 8).
The SRQ process asserts SRQ as true and sets the status byte’s RQS bit to 1. Both actions
are necessary to inform the controller that the N8211A/N8212A requires service. Asserting
SRQ informs the controller that some device on the bus requires service. Setting the RQS bit
allows the controller to determine which N8211A/N8212A requires service.
This process is initiated if both of the following conditions are true:
• The corresponding bit of the Service Request Enable Register is also set to 1.
• The N8211A/N8212A does not have a service request pending.
A service request is considered to be pending between the time the N8211A/N8212A’s
SRQ process is initiated and the time the controller reads the status byte register.
If a program enables the controller to detect and respond to service requests, it should
instruct the controller to perform a serial poll when SRQ is true. Each device on the bus
returns the contents of its status byte register in response to this poll. The device whose
request service summary (RQS) bit is set to 1 is the device that requested service.
NOTE
Multiple Status Byte Register bits can assert an SRQ, however only one bit at a time can set
the RQS bit. All bits that are asserting an SRQ will be read as part of the status byte when it
is queried or serial polled.
NOTE
When you read the N8211A/N8212A’s Status Byte Register with a serial poll, the RQS bit is
reset to 0. Other bits in the register are not affected.