A "new" vintage Oscilloscope on my workbench :-)

For issues with communication ports, protocols, etc.
D.J.Peters
Posts: 7667
Joined: May 28, 2005 3:28

A "new" vintage Oscilloscope on my workbench :-)

Postby D.J.Peters » Feb 27, 2018 13:05

To day I got an vintage Tektronix 2211 50 MHz Digital Analog Oscilloscope from eBay (~20$).
Image
Of course all this old (~1989) Tektronix and other Oscilloscopes does not have a USB interface
but many of them have a RS232C or centronics interface to plot the channels on pen plotters or printers.

I recorded with FreeBASIC the serial interface (9600 baud) from the device and the result are a HP-GL plotter file.

With a tiny HP-GL decoder in FreeBASIC you can plot this kind of data easly.

If you like to test it be sure the 4 channel demo file "PLOT.hpgl" are in the same folder.

Joshy

right click and save as: PLOT.hpgl

file: hpglplot.bas

Code: Select all

'#define DEBUG

#ifdef DEBUG
 #define DPRINT(msg) open err for output as #99:print #99,msg:close #99
#else
 #define DPRINT(msg) :
#endif

const HPGL_FILE = "PLOT.hpgl"

function getText(aLine as string,byref iPos as integer) as string
  var txt = ""
  while aLine[iPos]<>asc(";") andalso aLine[iPos]<>asc(",")
    txt &= chr(aLine[iPos])
    iPos+=1
  wend
  iPos+=1
  'DPRINT("txt: " & txt)
  return txt
end function

function getNumber(aLine as string,byref iPos as integer) as single
  var number = getText(aLine,iPos)
  return val(number)
end function

'
' main
'

ChDir EXEPath()
var FileName = HPGL_FILE

var hFile = FreeFile()
if Open(FileName,for binary,access read,as #hFile) then
  print "error: can't read " & FileName & "!"
  beep : sleep : end 1
end if

var nBytes = LOF(hFile)
DPRINT("file size: " & nBytes)
var buffer = new ubyte[nBytes]
get #hFile,,*Buffer,nBytes
close #hFile


dim as single ratio,xSize,ySize
dim as integer iRead,iPen,scrW,scrH,xMin,xMax,yMin,yMax,xPos,yPos,xOld,yOld
dim as boolean scrActive,penActive,labActive

screeninfo scrW,scrH
scrW*=0.75 : scrH*=0.75

while iRead<nBytes
  dim as string aLine '= ""
  while right(aLine,1)<>chr(asc(";"))
    if buffer[iRead]<>3 then
      aLine &= chr(buffer[iRead])
    end if 
    iRead+=1
  wend 
  var aCmd = left(aLine,2)
  var iPos=2
  select case aCmd
  case "DF" ' set default
    penActive=false ' no active pen
    labActive=false ' no active label
    iPen = 1
    xMin=0:xMax=scrW
    yMin=0:yMax=scrH
    xOld=0:yOld=0
    xPos=0:yPos=0
    DPRINT("reset to default")
  case "SP" ' set pen #
    iPen = getNumber(aLine,iPos)
    DPRINT("set pen color " & iPen)
  case "SC" ' scale
    xMin = getNumber(aLine,iPos)
    xMax = getNumber(aLine,iPos)
    yMin = getNumber(aLine,iPos)
    yMax = getNumber(aLine,iPos)
    DPRINT("scale " & xMin & "," & xMax & "," & yMin & "," & yMax)
    if scrActive=false then
      screenres scrW,scrH
      scrActive=true
    end if 
    if scrActive then window (xMin,yMin)-(xMax,yMax)
  case "PU" ' pen up
    penActive=false
    if aLine[iPos]=asc(";") then
      DPRINT("pen up")
    else
      xOld=getNumber(aLine,iPos)
      yOld=getNumber(aLine,iPos)
      DPRINT("pen up at " & xPos & "," & yPos)
    end if
  case "PD" ' pen down
    penActive=true
    if aLine[iPos]=asc(";") then
      DPRINT("pen down") 
    else
      xPos=getNumber(aLine,iPos)
      yPos=getNumber(aLine,iPos)
      xOld=xPos:yOld=yPos
      DPRINT("pen down at " & xPos & "," & yPos)
      'pset (xPos,yPos),iPen
    end if   
  case "PA" ' plot absolute
    xOld=xPos:yOld=yPos
    xPos=getNumber(aLine,iPos)
    yPos=getNumber(aLine,iPos)
    if penActive then
      DPRINT("plot to " & xPos & "," & yPos)
      if labActive then
        line (xOld,yOld)-(xPos,yPos),iPen
      else
        line (xOld,yOld)-(xPos,yPos),7
      end if 
    else
      DPRINT("move to " & xPos & "," & yPos)
    end if 
  case "SR" ' set relative character size
    xSize=getNumber(aLine,iPos)
    ySize=getNumber(aLine,iPos)
    'DPRINT("char size " & xSize & "," & ySize)     
  case "LB" ' label
    labActive=true
    var sLabel = getText(aLine,iPos)
    draw string (xOld,yOld),sLabel,15
    DPRINT("label: " & sLabel)
  case else
    DPRINT("unsupported HP-GL command " & aCmd)
    beep:sleep
  end select
wend

windowtitle "done ..."
deallocate buffer
sleep

click to enlarge:
Image
nastasa eodor
Posts: 55
Joined: Dec 18, 2018 16:37
Location: Germany, Hessdorf
Contact:

Re: A "new" vintage Oscilloscope on my workbench :-)

Postby nastasa eodor » May 07, 2019 23:29

nice and interesting.
marcov
Posts: 2748
Joined: Jun 16, 2005 9:45
Location: Eindhoven, NL
Contact:

Re: A "new" vintage Oscilloscope on my workbench :-)

Postby marcov » May 08, 2019 9:07

The value is partially how much memory they have. Some of the older scopes have very little memory, but some slightly later ones have quite some.

A customer had a Yokogawa scope, which hadn't been replaced because it was very expensive, fairly high speed and modular (16 channels, upgradable to 32 iirc), with a plotter or floppy for output. Probably cost 5 digits+, and the first might not have been a 1, specially after all the upgrades. The thing looked more like a cupboard than an instrument.

It was a leftover from when the customer still tested and built its own lines.

But the nice thing was that it had an insane long memory, so we had it wired up to a lot of channels, tried to trigger it on the first hint of corruption using other electronics and then scan back and look at the other channels to find out what started it. Since the problems were rare, monitoring many potential channels really saved time.

Return to “Hardware Interfaces / Communication”

Who is online

Users browsing this forum: No registered users and 0 guests