Edge Detected Event Detection

The HP E1459A can respond to two types of events: Edge Events (either negative edge, positive edge, or both) and Data Available. Figures 2-1 and 2-2 show the general flow of commands necessary to program the HP E1459A to detect events. Figure 2-1 shows the flow for Edge Event Detection, Figure 2-2 shows the flow for Data Available Event Detection.

Three general methods of identifying and servicing an HP E1459A detected event are:

Polling the Port Summary Register

Polling the VXI Status Subsystem

SRQ Interrupt

Polling the Port Summary Register

When an Edge Event occurs, read the value of the port(s) with the [SENSe:]EVENt:PORTn:NEDGe? or [SENSe:]EVENt:PORTn:PEDGe? command. When a Data Available Event occurs, read the value of the port(s) with the MEASure:DIGital:DATAn command.

The first, and easiest method, is to repeatedly poll the Port Summary Register using either the SENSe:EVENt:PSUMmary:EDGE? command (for Edge Events) or the SENSe:EVENt:PSUMmary:DAVailable? command (for Data Available Events) until an event occurs. Example 3 in this chapter demonstrates this procedure.

Polling the Status Subsystem

SRQ Interrupt

The second method is to set-up and repeatedly poll the Status Subsystem. You can poll the port summary condition register with the STATus:OPERation:PSUMmary:CONDition? command to determine when an event has occurred.

Alternately, set-up the port summary enable register to specify the type of event(s) and port(s) to monitor; use the STATus:OPERation:PSUMmary:ENABle<mask> command. Then enable bit 9 in the Status Operation Enable register; use the STATus:OPERation:ENABle command. Repeatedly poll the module with the *STB? command to determine when bit 7 becomes set.

The third method is to set-up the Status Subsystem and have the HP E1459A Module interrupt (via SRQ) the system computer when an event occurs. In general, you must set-up the port summary enable register to specify the type of event(s) and port(s) to monitor; use the STATus:OPERation:PSUMmary:ENABle<mask> command. Then, enable bit 9 in the Status Operation Enable register; use the STATus:OPERation:ENABle command. Enable the OPR bit (bit 7) in the Status Register with the *SRE 128 command; this allows the Operation Status register to generate the SRQ.

34 Using the HP E1459A Module