Tektronix 1180x Screen Capture Utility

Joel Koltner, May 2010


The Tektronix 1180x Screen Capture Utility (“TSC”) is a program that allows easy screen captures from a Tek 11802 oscilloscope using the serial port interface. It will likely work with any Tek 11800 series and perhaps even 11400 series scope, although I don't have these to test (...and the need for such a utility on, e.g., the 11801 is lessened as this model can directly output TIFF files).


Besides the obvious motive to be able to document waveforms without needing to grab a camera, I used this program as a learning exercise for the wxPython GUI toolkit. I mention this in that, while the program is “fast enough,” it's definitely not “screaming fast” and this is largely a result of Python as the programming language – interpret languages still seem noticeably slower than good compiled languages!

Setting Up Your Scope

Configuring your scope consists of (1) connecting a regular cable between your PC and the scope (this is a “straight-thru” cable – the scope is DCE) and (2) configuring the Utility->RS232C Parameters and Utility->Hardcopy screens. The RS232C parameters screen should end up looking like this:




The important bits are the baud rate, stop bits, parity, and flagging (aka, handshaking) – the rest doesn't really matter. (In fact, PCs seem to be fast enough these days that everything still works if you turn flagging off completely.)


Set the hardcopy parameters to look like this:




The important bits here are Printer, Direction, Data Format, and Output Port. The “binary compacted” data format was chosen because it produces the fastest possible screen dumps; if you inadvertently select another format TSC will likely just ignore the scope or possibly spew out an occasional error message. The “horizontal” direction was chosen arbitrary – supporting both is a straightforward addition to the program, but I didn't have need for it; if you inadvertently select it TSC will issue a warning when you press “hardcopy.” Finally, “screen format” is largely a matter of preference: Any except “Reduced” will work -- some are a little more detailed than others, some are a little faster than others. See the “Trivia” section below for details on why you shouldn't chose “Reduced.”

Program Usage

The program was written to be largely self-explanatory in its use. After physically connecting your 'scope to your PC, you proceed as follows:



That's all there is to it! Enjoy, and let me know if you find any bugs...


---Joel Koltner

zapwire-fun@yahoo.com

Trivia Learned About the Tek 11802



EOL String” Setting

Output Character(s)

CR/LF

0x83, 0xC4

CR

0x49

LF

0x69

LF/CR

0x9B, 0x2E

I expect this an artifact of the compression routines getting invoked when they shouldn't be.


I'd love to find some of the designers of this classic scope to discuss just how this classic instrument came about. These days the 11802 is more than two decades old, but it still holds great value for those interested in performing very high-speed time domain measurements on a budget.