Agilent Technologies E1439 manual Trigger Lines

Module Description

VXI backplane connections

Trigger Lines

The VXI specification provides 8 TTL and 2 ECL trigger lines that can be used for module- specific signaling. When programmed in a multi-input configuration, the E1439 uses the ECL trigger lines, designating ECLTRG0 as the SYNC line and ECLTRG1 as the 10 MHz Reference Clock (CLOCK). These lines can be extended to other mainframes using the SMB connectors on the front panel. The SMB connectors can also be used for intermodule synchronization within a mainframe, leaving the ECL trigger lines free for other purposes.

The CLOCK line is the master reference clock for a synchronous system of multiple E1439 modules. Only one E1439 module in each mainframe is allowed to drive this line.

The SYNC line is used to send timing signals among E1439 modules in a multi-input system. Any module that drives this line must do so synchronously with CLOCK so that transitions on SYNC do not occur near the rising edge of CLOCK. This ensures that all modules with a synchronous state machine clocked on CLOCK interprets SYNC in a consistent manner for each cycle of the state machine. SYNC is used for synchronizing, arming, and triggering signals between E1439 modules. The interpretation of the SYNC line is dependent on the states of the module described in “The measurement loop” on page 23. The E1439 module is also capable of controlling the SYNC line synchronously via the control register.

For more information on multi-module operation see “Managing multiple modules” on page 32.

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