The following options are available to purchase and enhance the functionality of the M2i.20xx, M2i.46xx A/D and M2i.70xx digital I/O boards.
| ABA mode | Synchronisation by star hub | Multiple recording / replay | Gated sampling / replay | BaseXIO | Time stamp |
ABA mode this allows changing from long-term slow and continuous data logging (through a process of sample decimation), to ultra-fast acquisition on a trigger event. This is handled by the hardware. This is more efficient than having to write code in a post-process program and helps isolate in detail interesting events from reams of data.
In the above diagram the decimated data capture points are shown as blue lines. When a trigger is applied the data is recorded at the full clock speed, here depicted by the green lines in section B. Data is captured for a user definable numbers of times. Pre and post trigger data can be recorded at the full rate if required so that analysis of the signal leading up to the trigger, as well as that following can be performed.
ABA mode significantly reduces stored file sizes. At the sort of rates these ultra high-speed cards can operate, this is a big advantage. The level of decimation can be set in the driver code or the SBench software. The trigger point can be external an TTL pulse, or from the amplitude of the analogue input signal.
The Star Hub is an additional module for all M2i boards. It allows synchronisation up to 16 boards with no phase delay between them. With this option, multi-channel acquisition systems of up of to 128 analogue channels (512 if its digital I/O) are possible. Any combination of boards can be synchronised be it analogue or digital, in signal capture or generation mode. The 5 card version of the Star-Hub (code: M2i.xxxx-SH5 ) allows synchronisation without the need for an additional system slot, as the star hub connectors are very compact.
Across the Star Hub, clock and trigger information is common and exchanged between all the boards. Division of the clock from the board defined as master allows connected slave cards to be run more slowly, if required, providing for great flexibility for sampling speeds across the system, but all still held in phase. Any board may be used to generate the trigger used by the system to initiate recording.
System Synchronisation
with Star Hub
With the M2i series comes the ability to synchronise several systems (i.e. a number of PC's all populated with Spectrum boards). This option is ideal for where all slots within one PC have been used. It also provides a solution where data needs to be stored at extreme speeds to a hard disk (e.g. using RAID), but the PCI/PCI-X bus bandwidth on a single PC motherboard has been exceeded. Similar in operation to the aforementioned Star Hub with its master board for clock and trigger, System Star Hub has one whole system (PC) as the master, with ribbon cable connected slave systems of 5 or 16 boards. Up to 271 boards of any type (A/D, D/A and Dig I/O) can be combined in this way - all perfectly synchronised!
PCI/PCI-X system external synchronisation
by distribution card
As an alternative to the Star-Hub it is is also possible to use the Spectrum distribution card (code: M2iClkDist), this allows external access to all clock and trigger lines via external cabling, so the user can decide whether to synchronise all cards, or a number to be excluded and work asynchronously. Up to 34 cards can be synchronised on from the same clock source, or two banks of 17 clocks, each bank of 17 operating from an independent clock. Lastly it is possible to have a bank 17 clocks and a bank of 17 triggers. The distribution card makes all the wiring and used the standard Spectrum SMB screened cables, logical and easier to manage.
[PDF data sheet for distribution card]
(160K byte)
Multiple Recording allows the capture of signal data associated with each of several trigger events, without having to restart the hardware. Trigger events which repeat at a very high rate could thus be recognised with this option without risk of any being missed. A trigger re-arm period is required immediately after each capture event, however for the M2i series of boards this is less than 4 samples in length. Should the user intentionally wish for an extended delay between trigger arrival and each recording this is software programmable too. Note than the M2i.70xx digital I/O boards, being also capable of providing output signals, can use a similar mechanism in the opposite direction to rapidly play sequences of bit patterns in response to very rapid repeat triggers.
The memory of the board will be divided into several segments of the same size. Each segment will be filled with data (or played from) when a trigger event occurs.
When using boards of the M2i.xxxx series, Multiple Recording/Replay may be combined with the Time stamp option to very usefully record the start time of a segment.
The option Gated Sampling allows recording of a signal controlled by an external gate signal. Data is only recorded if the external gate signal is equal to a programmed level (TTL HIGH or TTL LOW). As with the Multiple-Recording option (see above) a delay of a few samples between trigger and recording occurs, but again easily compensated for by pre-trigger samples.
For the Mi.70xx series where a signal output is also possible, data is played whilst the external gate signal is equal to a programmed level (TTL HIGH or TTL LOW).
As an option on some boards, the start and end sample of a gate interval may be marked in memory by combining with the Time stamp option to record start and end of a gate interval.
BaseXIO (Asynchronous I/O and triggers).
This option provides digital input and output lines asynchronous to the analogue inputs of A/D cards, or digital I/O lines of the universal digital I/O cards. One of the advantages is their 32mA source capability, so that with this simple-to-use versatile enhancement it is possible to control a wide range of external instruments or other equipment, such as that producing a signal source. Eight asynchronous digital I/O are available and can be programmed 8 inputs, 8 outputs or split 4/4. When using the BaseXIO lines as digital I/O, they are completely independent from the board’s function, data direction or sampling rate and directly controlled by software. Special purpose lines are also added to provide two secondary TTL trigger lines to allow an AND type operation within the main external trigger starting the board. So for example you can start and stop the board by monitoring a condition at two sources. Finally a RefClock input comes with this option to allow the Time Stamp option (see below) to accept a precise 1Hz pulse from an external timer card.
 | The time stamp function allows recording of trigger moments relative to the start of recording or synchronised to an external radio clock. The time stamp function is designed as an enhancement to the Multiple Recording and the Gated Sampling mode but could also be used without any of these options. The memory of the time stamp function is a FIFO buffer and this allows continuous signal recording with time stamps. Each time stamp is defined by samples and therefore the rate of the A/D converter clock. The relationship between trigger events and the count are set by the modes as described below. |
Standard Mode
In standard mode the time stamp counter is set to zero once, with a call to TS_RESET. After this call the counter counts continuously. The time stamp of all recorded trigger events are referenced on this common zero time. With this mode the exact time difference between different recordings may be calculated.
StartReset Mode
When card is started ready for a trigger it will not to start to record data until a trigger is received. In multiple record mode many such trigger events may be very close together to capture many such individual recordings and when each such recording segment is finished the board is automatically re-started ready for the next trigger. In the StartReset mode a time stamp value is given calculated from the counter which starts from zero after each current restart. In addition, if this is used instead with gated sampling, a time stamp will show the start and also the end of the gate.
RefClock Mode
The counter is divided in a HIGH and a LOW part. The HIGH part counts the seconds that have elapse since reset of the whole counter and references the seconds signal of an external radio clock, or any user precise 1Hz signal. The LOW part is reset every second, and defines the position of the trigger event within the current second. The timing signal must be fed into the time stamp module as a TTL signal. This mode allows the absolute time of a trigger event to be recorded. Alternatively, the HIGH counter part could also be used to count the number of external triggers. N.B. The Refclock connector interface requires the BASEXIO option
Click for more information plus diagrams on Time stamp [Time stamp presentation]
The most popular option above called Multiple-Recording can be purchased on its own
The BASEXIO is an individual purchase for each board, however with the Star-Hub synchronisation only one purchase is required per system of boards. |
| [Top] | [Home Page] |
© Dataquest Solutions 14.01.06.
Images courtesy of Spectrum GmbH