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M3i.48xx / M3i.48xx-exp Manual
Recording modes
Mode Multiple Recording
Mode Multiple Recording
The Multiple Recording mode allows the acquisition of data
blocks with multiple trigger events without restarting the hard-
ware.
The on-board memory will be divided into several segments of
the same size. Each segment will be filled with data when a trig-
ger event occurs (acquisition mode).
As this mode is totally controlled in hardware there is a very
small re-arm time from end of one segment until the trigger de-
tection is enabled again. You’ll find that re-arm time in the tech-
nical data section of this manual.
The following table shows the register for defining the structure of the segments to be recorded with each trigger event.
Each segment in acquisition mode can consist of pretrigger and/or posttrigger samples. The user always has to set the total segment size
and the posttrigger, while the pretrigger is calculated within the driver with the formula: [pretrigger] = [segment size] - [posttrigger].
When using Multiple Recording the maximum pretrigger is limited depending on the number of active chan-
nels. When the calculated value exceeds that limit, the driver will return the error ERR_PRETRIGGERLEN.
Please have a look at the table further below to see the maximum pretrigger length that is possible.
Recording modes
Standard Mode
With every detected trigger event one data block is filled with data. The length of one multiple recording segment is set by the value of the
segment size register SPC_SEGMENTSIZE. The total amount of samples to be recorded is defined by the memsize register.
Memsize must be set to a a multiple of the segment size. The table below shows the register for enabling Multiple Recording. For detailed
information on how to setup and start the standard acquisition mode please refer to the according chapter earlier in this manual.
The total number of samples to be recorded to the on-board memory in Standard Mode is defined by the SPC_MEMSIZE register.
FIFO Mode
The Multiple Recording in FIFO Mode is similar to the Multiple Recording in Standard Mode. In contrast to the standard mode it is not nec-
essary to program the number of samples to be recorded. The acquisition is running until the user stops it. The data is read block by block
by the driver as described under FIFO single mode example earlier in this manual. These blocks are online available for further data process-
ing by the user program. This mode significantly reduces the amount of data to be transferred on the PCI bus as gaps of no interest do not
have to be transferred. This enables you to use faster sample rates than you would be able to in FIFO mode without Multiple Recording.
The advantage of Multiple Recording in FIFO mode is that you can stream data online to the host system. You can make real-time data pro-
cessing or store a huge amount of data to the hard disk. The table below shows the dedicated register for enabling Multiple Recording. For
detailed information how to setup and start the board in FIFO mode please refer to the according chapter earlier in this manual.
The number of segments to be recorded must be set separately with the register shown in the following table:
Register
Value
Direction
Description
SPC_POSTTRIGGER
10100
read/write
Acquisition only: defines the number of samples to be recorded after the trigger event.
SPC_SEGMENTSIZE
10010
read/write
Size of one Multiple Recording segment: the total number of samples to be recorded after detection
of one trigger event including the time recorded before the trigger (pre trigger).
Register
Value
Direction
Description
SPC_CARDMODE
9500
read/write
Defines the used operating mode
SPC_REC_STD_MULTI
2
Enables Multiple Recording for standard acquisition.
Register
Value
Direction
Description
SPC_MEMSIZE
10000
read/write
Defines the total number of samples to be recorded.
Register
Value
Direction
Description
SPC_CARDMODE
9500
read/write
Defines the used operating mode
SPC_REC_FIFO_MULTI
32
Enables Multiple Recording for FIFO acquisition.
Register
Value
Direction
Description
SPC_LOOPS
10020
read/write
Defines the number of segments to be recorded
0
Recording will be infinite until the user stops it.
1 … [4G - 1]
Defines the total segments to be recorded.
