LTSpice not displaying voltage probes - Page 1
Forum section: electronics / beginners

author: xander18
author_rank: Newbie
timestamp: January 27, 2016, 04:42:24 am
content: Hey all,My install of LTSpice IV doesn't show the actual voltage probes on the schematic after running the simulation. It plots it out but the actual markers don't show up on the schematic. I can't seem to find an option for this and no mention in LT literature. It would be a nice feature to have.Is this a bug and can anyone help me squash it?Relevant xkcd:https://xkcd.com/979/

author: Dago
author_rank: Frequent Contributor
timestamp: January 27, 2016, 06:05:53 am
content: I don't think there are any visible probes in ltspice. The traces shows the nodenames ("V(n001)" etc.) which I agree is not terribly handy...

author: Ian.M
author_rank: Super Contributor
timestamp: January 27, 2016, 06:26:38 am
content: Label the nodes you are interested in and the waveform viewer will use those labels. Its a kludge that demands preplanning but its easier than mouseovering to locate node numbers once you have several similar traces active.

author: macboy
author_rank: Super Contributor
timestamp: January 27, 2016, 02:17:37 pm
content: You can have LTSpice show DC voltages directly on schematic nodes. Close the plot window that automatically opens when the simulation is run. Now just left click the nodes to place the voltage markers. If the plot window is open, then you have only the probe tool for displaying plots of nodes, that's why you need to close the plot window first. The DC voltages shown are based on the solution to the the initial DC operating point, so make sure not to select "Start DC supply voltages at 0V" in the sim options.

author: xander18
author_rank: Newbie
timestamp: January 27, 2016, 03:09:09 pm
content: Dago, I guess that would settle it. I was looking for indicators like the ones in OrCAD Pspice (http://www.alciro.org/images/alciro/1208_pspice-sondas-de-se%C3%B1al.png). I just assumed they would be there... whatever, just an inconvenience and the price is right!Thanks everyone else for the other features and tips, I'll use something like that.

author: Ian.M
author_rank: Super Contributor
timestamp: January 27, 2016, 04:19:37 pm
content: You can also right click and use the view sub-menu to place a .op label (usually a node voltage display label as discussed above) absolutely anywhere on the schematic background with the waveform window still open. If it isn't on a node it will show as ? ? ?. Right click it and you get a list of data values it can display. If you leave the expression as $ it displays the voltage of the node its connected to. but you can delete that, and click any of the list instead, or even do maths on them.See 'Waveform Arithmetic' in the help for valid functions and operators, or you can define your own. e.g:If you add the function:Code:.func dp(x,y) {round(x*(10**y))/(10**y)}to your plot defs file, you can easily round them to the desired number of digits. However this rounding is done on the base unit, so if it for example is displaying in mV, you'll need to use dp($,5) to get 2 digits after the decimal point rather than the dp($,2) you would expect which would work if the node voltage was large enough to display in volts.Seehttp://ltwiki.org/index.php5?title=Undocumented_LTspice#Operating_Point_Data_Labels_.28visible_numeric_dc_bias_values.29