Test and Measurement Forum

Trigger OK with B, but not EXT

Post any questions you may have about our current range of oscilloscopes

Trigger OK with B, but not EXT

Postby lesica » Wed Apr 27, 2011 2:12 pm


I've got a 4226 and I'm trying to use the external trigger. When I send my trigger signal into B and try to trigger of it, it works great. When I send the same signal into EXT and try to trigger off it with the same threshold, it doesn't work. Am I missing something silly?



Re: Trigger OK with B, but not EXT

Postby Chris » Thu Apr 28, 2011 3:40 pm

We have found a problem with the external trigger on the 4226 / 4227.

Please email support@picotech.com for a modified driver.
Site Admin
Site Admin
Posts: 169
Joined: Tue Aug 17, 2010 9:00 am
Location: St. Neots

Re: Trigger OK with B, but not EXT

Postby bignon.frederic » Wed May 02, 2012 7:57 am

Hi Chris,

I use a picoscope 4227.
When I send a TTL signal on the EXT input with a 0.5V high level to begin analog signal acquisition on the A or B input, it doesn't work. If the high level value is higher (1 to 4 Volts for example), the trigger works well.
I suppose that the problem comes from the trigger threshold (16-bit counts) value of trigger settings sent to ps4000SetSimpleTrigger function.
I tried different values because I didn't find any information in the datasheet. Above value 480 the trigger doesn't works at all. For 100 or 200 it works from time to time.

Moreover after reading the post of LESICA on the forum, I wonder if I have the same problem that LESICA.
Should I use the modified driver that you mention ?


Fred Bignon
Posts: 0
Joined: Tue Mar 13, 2012 10:05 am

Re: Trigger OK with B, but not EXT

Postby Martyn » Wed May 02, 2012 9:52 am

Are you using the scope with Picoscope6 software and if so which version ?
Technical Support Manager
Site Admin
Site Admin
Posts: 3217
Joined: Fri Jun 10, 2011 8:15 am
Location: St. Neots

Return to USB PC Oscilloscopes

Who is online

Users browsing this forum: No registered users and 0 guests