Why is the trigger point in the center of the screen - Page 1
Forum section: electronics / testgear

author: conducteur
author_rank: Regular Contributor
timestamp: December 18, 2018, 08:31:22 pm
content: I'm working with my rigol DS1054Z on a project with PIC microcontrollers. I use the scope to debug serial communication between the PIC's. Like on other scope's i used in the past, the trigger point is in the horizontal center of the screen. Isn't it more logical to have the trigger point on the left, to use the whole display to plot the signals that you've sampled after the trigger? Is there a reason why they put it in the center? Are there any scopes on the market that can set the default trigger on the left?

author: tautech
author_rank: Super Contributor
timestamp: December 18, 2018, 08:44:40 pm
content: Quote from: conducteur on December 18, 2018, 08:31:22 pmWith scopes it can be useful to see the pre-trigger waveform and a center position is default for DSO's.Just using Horizontal Pos allows you to have it anywhere you like but when changing the timebase to a faster setting the trigger point is displaced off screen unless there is provision to have it in a fixed position irrespective of timebase setting.Many higher priced DSO's have this 'fixed' trigger point feature and also the new SDS1*04X-E models.It's easily accessible in the Utility menu:Go to  -> Reference Position.Select Horizontal "Constant Position" instead of "Constant Delay".Edit to add:The X-E models allow for a full set of user definable settings .....your favorite scope setup....all can be assigned to the Default button so that when finishing a project you can return the DSO to just how you like to kick off again with it.

author: 0xdeadbeef
author_rank: Super Contributor
timestamp: December 18, 2018, 08:44:59 pm
content: A trigger point on the very left would be impracticable for most analog waveforms. I.e. when you trigger on 50% on a rising slope, the half of the slope would be missing.In the end the problem is that the scope (or its designers) can't know if you're interested in the signal before or after the trigger. So displaying the trigger in the middle is a pragmatic compromise I guess.

author: RoGeorge
author_rank: Super Contributor
timestamp: December 18, 2018, 08:53:41 pm
content: I like the trigger point to be at the beginning of the screen, too.A workaround would be to send SCPI commands that put the trigger on the left side of the screen each time the time base is adjusted.

author: Bud
author_rank: Super Contributor
timestamp: December 18, 2018, 08:56:20 pm
content: My ancient Tek 2430 has trigger position adjustable. So this should not be a rocket science to have in a modern scope.

author: TheSteve
author_rank: Unknown
timestamp: December 18, 2018, 08:58:44 pm
content: The Tek THS7x0 series of handheld scopes let you have the trigger at 10%, 50% or 90% - it was quite handy to use 10% at times.

author: RoGeorge
author_rank: Super Contributor
timestamp: December 18, 2018, 09:06:35 pm
content: Something like this might be handy:https://hackaday.io/project/13317-scope-keys

author: Fungus
author_rank: Super Contributor
timestamp: December 18, 2018, 09:09:47 pm
content: Quote from: Bud on December 18, 2018, 08:56:20 pmYou can turn a knob and move it on a DSO, no problem.I always thought it would be better to have it 1/3 of the way across the screen - best of both worlds (ie. analog and digital worlds).

author: Fungus
author_rank: Super Contributor
timestamp: December 18, 2018, 09:12:19 pm
content: Quote from: conducteur on December 18, 2018, 08:31:22 pmIt probably is more logicalfor serial decodingbut not for looking analog waveforms, eg. sine waves. For that sort of wave you usually want a zero crossing right in the center of the screen.

author: rf-loop
author_rank: Super Contributor
timestamp: December 19, 2018, 07:13:13 am
content: Quote from: TheSteve on December 18, 2018, 08:58:44 pmWith Siglent X-E series user have full freedom for set and fix trigger position, not only 10, 50, 90%. Just select Horizontal reference position type "Fixed Position" instead of "Fixed Delay" and then adjust your trigger position where ever you want. After then if you change t/div trigger position stay in this position on the screen. (factory default mode is "Fixed Delay". In this mode if delay is zero it is center of screen and if you set example 1us delay it keep this delay time when change t/div)Horizontal Fixed Position (trigger position) is very handy in many cases.Then, example if want capture lot of separate messages to history buffer (using normal mode or sequence mode) for later decoding, set trig position near left example 1% so you have more memory length for every message if you trig starting of message.And, of course there is same kind of set for vertical. You can select fixed offset or fixed position. Fixed position is default. As know this leads in some cases frustrating adjusting vertical position when you change t/div in situations you need use offset. With fixed offset voltage - just nice.

author: photomankc
author_rank: Contributor
timestamp: December 19, 2018, 03:08:14 pm
content: Awesome, I'll have to file that away! Didn't grok that when reading up on the trigger. I've wished for that quite a few times.

author: nctnico
author_rank: Super Contributor
timestamp: December 19, 2018, 10:16:02 pm
content: Quote from: conducteur on December 18, 2018, 08:31:22 pmOn most higher end oscilloscopes you can adjust the position of the trigger point. On some it is freely adjustable, on others you can choose left, right or middle. Left and right are usually one division away from the side of the screen.