Instruction manual

Mode:

• live: EL_LIVE

• snap: EL_SNAP

• or be aborted: EL_ABORT

RETURN VALUE:

0 if OK

-1 if ERROR See el_GetErrorCode for details.

DESCRIPTION:

Single buffer acquisition:

EL_LIVE: switches to live mode. A continuous real-time acquisition takes place.

EL_SNAP: If acquisition is in live mode the acquisition is terminated after the current image has been

acquired. If not in live mode, the acquisition is started for a single frame/field. The acquisition stops

automatically after one frame/field has been acquired. Use el_TestAcq to wait for acquisition complete.

Image sequence acquisition:

An image sequence is defined with el_InitHW or el_NewMemBuffer if a FrameCount greater than '1' was

supplied. Then the following behavior can be expected with el_Acquire :

EL_LIVE starts an endless sequence acquisition (ring buffer acquisition). In such a case the number of

the current frame can be inquired with el_TestFrameCount .

EL_SNAP acquires exactly one sequence ( number of frames acquired is equal to FrameCount ). Use

el_TestFrameCount to detect the acquisition of a frame inside a sequence or el_TestAcq to wait for the

whole sequence to complete. See also: Sequences

Acquisition and external trigger:

If an external trigger is supplied to control the acquisition, the video hardware should be switched to live

mode (call el_Acquire with parameter mode set to EL_LIVE). In case of single-buffer acquisition each

trigger pulse causes the hardware to acquire exactly one frame/field. In case of sequence acquisition

each trigger causes the hardware to acquire one frame of the sequence. If you call el_Acquire with mode

set to EL_SNAP, the first following pulse causes an acquisition. Every following pulse has no effect.

Therefore, EL_SNAP can be used to disable external trigger acquisition temporarily. EL_ABORT can be

used to disable image acquisition imediately.

CAVEATS:

el_Acquire returns immediately. Therefore, el_TestAcq has to be used to determine the end of an

acquisition. There are several other options to inquire the status of an acquisition. Refer to the

descriptions of the different el_Test functions supplied in the on-line help.

If live mode is selected and image processing as well as display is active during acquisition, the PCI bus

bandwidth may be exceeded, which can be seen from a rolling picture .

EXAMPLE : see el_OpenHW