Agilent Technologies VXI E1439 - Manual (Page 161)

151
Agilent E1439 Programmer's Reference
Functions listed alphabetically
age1439_meas_control
Initiates and controls measurements in multi-module systems.
VXIplug&play Syntax
#include "age1439".h
ViStatus age1439_meas_control(ViSession id, ViInt16 idle, ViInt16 sync);
Description
age1439_meas_control explicitly controls the measurement state.
Parameters
id is the VXI instrument session pointer returned by the age1439_init function.
idle selects the condition of the Idle state.
AGE1439_ASSERT holds the module in the Idle state.
AGE1439_RELEASE reverses a previous AGE1439_ASSERT or ensures that no forced Idle is
active.
sync selects the state of the sync signal.
age1439_meas_control also changes the state of the Sync signal, which is used to arm or trigger
an Agilent E1439 module. In systems containing multiple Agilent E1439 modules the Sync signal
is used to arm or trigger all modules simultaneously, and also to synchronize decimation counters
and local oscillators among the Agilent E1439 modules.
AGE1439_ASSERT causes the module to assert the Sync signal.
AGE1439_RELEASE causes the module to release the Sync signal. When parameters of the
age1439_clock_setup function which enable sync output are selected the module shares the sync
signal with other Agilent E1439 modules. If any one of these modules asserts this shared Sync
signal it then becomes asserted for all of them. All modules must release it before the shared Sync
signal is released. Asserting then releasing the Sync line is used to start a measurement, load local
oscillator values, or take a digital filter out of reset. These situations require a Sync line transition
but do not require that the Sync line be held in a asserted state.
Note
When the Sync line is asserted, it remains asserted for an adequate number of ADC clock cycles
to ensure that the signal effect propagates to all the modules in the system. You can determine
when the command is completed by looking as the Sync/Idle Complete bit in the Status Register.
Note
Any command that halts the current measurement ( See “Commands which halt active
measurements” on page 198 ) also releases the forced Idle and Sync controls. If
you want to hold a module in Idle after one of these commands you must call
age1439_meas_control again after the command that halted the current measurement.
Comments
See “The measurement loop” in chapter 3 for details on how a measurement progresses through
the four states.