How to create a trigger with Labview

[COmpa]

Hi all,
i've this strobo lamp Perkin Elmer MVS 4100
(http://pki8.mondosearch.com/cgi-bin/MsmGo.exe?grab_id=0&EXTRA_ARG=&host_id=42&page_id=20717&query=4100)

and it does have a 9pin connector for the External Trigger.
Do you think is possibile to connect it to the serial port of the pc
and create via Labview the Trigger?
The strobe needs a +5V, 20mA,10-100µsec pulse to be triggered.

THanks in Advance.

[tbd]

Hi COmpa,

---

Do you think is possibile to connect it to the serial port of the pc
and create via Labview the Trigger?
The strobe needs a +5V, 20mA,10-100µsec pulse to be triggered.

---

I think the 9-pin serial port on a PC swings between +/- 12V - if that's OK for your trigger, then a pulse of precise duration might be generated by configuring the port for serial output, a suitable baud-rate, careful selection of start or stop bit, and then sending a single byte byte where all bits are the same.  I've never done this, but I think it's possible!

If the +/- 12V is a show-stopper, then consider using a parallel-port instead.  Its pins swing between 0 and 5V.

http://zone.ni.com/devzone/conceptd.nsf/webmain/72C6FC6CE4AD4D1386256B1800794596

Also, a "quick and dirty" way to control pins on either the serial port or parallel port is by writing to a VISA property node:

Have fun!

Message Edited by tbd on 06-28-2006 11:52 PM

[thescar]

Hi all,
i'm working with compa at the same project
we have some new hardware that maybe could help us to generate the trigger

its a NI PCI 6229
with a connector block SCB68

how can we set labview to generate the trigger with this settings:

+5V, 20mA,10-100µsec
here you have a pic of the connector scheme
http://img95.imageshack.us/my.php?image=9pinconnector6dz.jpg


TIA.

G.

[tbd]

Hi G., COmpa,

      The link you provided indicate a TTL level pulse is required.  I'd use one of the 6211's counters for this.  Check-out the  "Gen Dig Pulse.vi" in EXAMPLES.

If for some reason this pulse is too weak, you ought to be able to get a precise pulse using one of the Port 0 digital outputs  - check-out "Buffered Pattern Output.vi".

There are also analog outputs available on this board, but it looks like the DIO are capable of sourcing more current - and the buffered [port 0] DIO allows precise pulse duration.  Looks like a really nice board!

Cheers.

Message Edited by tbd on 07-06-2006 03:18 AM

[thescar]

Hi TBD,
thanks for suggestion i'll check them out soon.
do you think that the "Custom_Pulse_Generator" example could work as well??
and what about the PIN 4 (RTN) on the 9 pin connector?? should i connect it to the connector Block too?.

Thanks

Regards,

G.

[thescar]

Hi,
i've checked the Example you suggested me.
The only doubt i've is about how to connect the Lamp to the Connector block.
i've a cable that has the Connector 9Pin D with the Pin 5 that is the Trigger +
and the Pin4 that is the Trigger - .....on the other side of the cable i've the corresponding wires.
When i open the Gen Dig Pulse.vi  example it says that the signal output is on Counter0 output
so i guess i've to connect it to the Trigger + pin, but what about the Trigger - ???
where i should connect the Trigger - wire on the Connector Block.

HELP.

G.

[J.Harv]

thescar--

    What to hook the trigger - pin to is really dependant on what this pin is used for.  It could be a ground but I would recommend looking in the manual for your device, or getting in touch with the manufacturer. So that you know for sure.

John H.

Applications Engineer

National Instruments

[tbd]

Hi G.,

      John is right, you're in the best position to answer these questions as you [should] have all the specs!

However, I'd have said "yes" - trigger- should go to any one of the "D GNDs".

Cheers.

[thescar]

Dear Friends,

all the informations about the connector and the pins that i've are in the pic that follow:

http://img95.imageshack.us/my.php?image=9pinconnector6dz.jpg

I've contacted the manufacture several time and thats what i get.

G.

[J.Harv]

thescar--

    Basically, you will need to call the manufacturer.  If they say look at the diagram, tell them you already did and it didn't help.  Be persistant.  We at NI cannot recommend anything since it is not our instrument. 

   What happens if you just hook up the signal without the trigger neg pin??  Does it work?  I mean it might not be necessary. On the other hand that pin could be a ground.  That was my first impression, the same as tbd.  Then it would be for a Single Ended Reference connection (one signal one ground for ref.).  In that picture it says the tigger signal goes to both, so like a differential connection (both connections are signals and common node voltage is rejected) your trigger signal would be wired to both.  I really don't know.

   You could play with it but I would HIGHLY recommend getting in contact with the manufacturer first.  You could cause a ground loop and break the instrument.  It is really up to you. Good Luck.

John H.

Applications Engineer

National Instruments