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EX10xxA Programming

111

Example: This code block sets a timer interval of 50 ms.

vtex10xxA_set_trigger_timer(vi, 0.05);

The current timer interval is queried with the

vtex10xxA_get_trigger_timer

query.

The LXI alarm is configured using the

vtex10xxA_self_test

_init function

vtex10xxA_set_alarm_enable

call can be performed,

vtex10xxA_set_alarm_enable

must be set

to false.

Normally,  each  acquisition  sequence  is  initiated  by  a  trigger  initialize  function.  However,  this
requirement  can  be  circumvented  through  the  use  of  init  continuous  mode.  Specifically,  init
continuous returns the trigger model to the entrance of the ARM layer without the requirement of a
new  trigger  initialize  function.  This  allows  for  a  specific  acquisition  sequence  to  be  restarted
automatically.  The  enabling  of  init  continuous  mode  is  done  with  the

vtex10xxA_set_init_cont

function. This function simply accepts a Boolean value indicating the enable status of init continuous
mode.

The current setting of init continuous mode is queried with the

vtex10xxA_get_init_cont

query.

Resetting the trigger model configuration

The

vtex10xxA_reset_trigger_arm

function is used to return all of the EX10xxA’s trigger

configuration parameters to their default values. It is similar to the

vtex10xxA_reset

function,

except that only trigger configuration parameters are affected. These parameters and their reset
values are documented in Table 6-1.

NOTE

The extensive flexibility of the trigger model system permits the creation of very specialized trigger
conditions,  which is a powerful application tool. However, it also permits the creation of trigger
conditions that  would be very difficult to satisfy in practice. For example, if edge conditions are
specified on multiple digital hardware channels, the edges must occur within 25 ns of each other to
be  recognized  as  having  occurred  simultaneously.  Similarly,  the  timer  source  should  not  be
combined with any digital hardware edge conditions.

NITIATE THE

RIGGER

ODEL

A trigger initialize is performed with the

vtex10xxA_init_imm

function. Upon the receipt of this

function, the trigger model transitions out of the IDLE layer and begins waiting for the ARM event.
This function clears the FIFO reading memory and resets all limit indications.

Once the trigger model has transitioned out of the IDLE layer, most instrument configuration
controls are disabled. An acquisition can, however, be aborted at any time with the

vtex10xxA_abort

function. An abort does not affect any stored acquisition data.

ONFIGURE THE

LXI

RIGGER

The primary use of the trigger bus is the transmission of high-speed signals for multiple-unit
triggering and synchronization. Accordingly, it can be used for input and output operations. Each
LXI Trigger Bus (VTB) channel can be independently programmed with regards to its output
functionality, its static level to assume when enabled as an output, and pulse operation.

The

vtex10xxA_get_vtb_input

query is used to obtain the measured digital level (0 or 1) of the

VTB channels. The input monitoring functionality operates regardless of the simultaneous use of
the channels as outputs. The response to this query is a decimal value from 0 to 255 that represents
the 8-bit value of the bus. Within the 8-bit field, the MSB corresponds to VTB channel 7 and the
LSB corresponds to VTB channel 0.

Example: This code block queries the state of the trigger bus and reports the level of bits 7, 4, and 0.