NAME

tekdump - handle screendumps from Tektronix 11801A or DSA602 oscilloscope

SYNOPSIS

tekdump [ -b
baud ] [ -l
device ] [ -BUmvh ] [ -t
type] prefix

tekdump [ -BUmv ] -f
file

DESCRIPTION

Tekdump provides a convenient mechanism for capturing screen images from
Tektronix oscilloscopes, such as the 11801A digital sampling oscilloscope or
DSA-602 digitizing signal analyzer. A suitable cable is connected from the
oscilliscope's EIA-232 port to a serial port on a host workstation; tekdump runs
on the host and listens for data over the serial port. When the ``Hardcopy''
button on the front panel of the 11801A or DSA602 is pressed, it sends a bitmap
image of the screen out the serial port. Tekdump writes each screen image to its
own file on the host.

It takes about 30 seconds for each screen image to transfer over the serial
port. The oscilliscopes have buffer memory for several screen images, so a
hardcopy can be requested several times in succession before this transfer rate
becomes a serious impediment.

OPTIONS

-B

Expect the screendump data from the scope to be in binary instead of what
the manual calls ``BinHex'' format. This doesn't work yet, but might speed up
the transfers slightly when I do get to it.

-U

Expect the screendump data from the scope to be in uncompressed form. The
scope's hardcopy data format setting must be adjusted correspondingly. They
take a long time to transfer this way.

-b baud

Set the serial port to the specified baud rate. The serial port on the
scope must be set to the same rate.

-f file

Convert raw screen dump data in file to the selected bitmap
format. This is useful mainly for debugging tekdump itself. The -b , -l ,
and -t
options are disallowed in this mode.

-h

Print ``hash marks'' (the ``#'' character) on the screen to indicate
progress while recieving a screen dump from the scope.

-l tty

Listen on the serial port device named tty instead of the
default.

-m

Convert the screen image from color to monochrome black-on-white form. The
color pallette used by the scope is such that some menu label text invariably
comes out unreadable under any simple mapping of the eight 11801A colors to
black and white, so this isn't all that useful.

-t type

Write the screen images in files of the specified type instead of
in the default portable pixmap (ppm) format. Available types are:

gif

GIF format files named with a suffix of .gif. Use of this
type requires that the ppmtogif executable be in your
$PATH.

tiff

Tagged Image Format files named with a suffix of .tiff. Use
of this filetype option requires pnmtotiff.

gzip

Ppm format files compressed with GNU zip and named with a suffix of
.ppm.gz. Use of this type requires that gzip be in your
$PATH.

.

-v

Operate in verbose mode. This can be useful for infering what's wrong when
things don't work.

.

EXAMPLES

For typical screendump-server usage:

tekdump -h -t gzip data

will listen on the default serial port at the default baud rate for
information from the scope, and store successive screendumps in files named
data0.ppm.gz, data1.ppm.gz, and so on. It will print "hash marks" to indicate
progress while receiving a screen dump.

HARDWARE SETUP

Cables.

The Tektronix oscilliscope's RS232 port is a DCE, so a "straight through"
RS232 cable is usually required for the connection. Since XON/XOFF flow control
is used, only a three-wire connection is required for transmit and receive data
and ground. A cable that works properly with a modem will probably work for this
application.

Tektronix 11801A and DSA602 setup.

Press the Utility button on the 11801's front panel, and select the
``Hardcopy Parameters'' menu item with the touchscreen. Set ``printer'' to
``Bitmap dump,'' direction to ``horizontal,'' screen format to ``screen,'' data
format to ``BinHex Compacted'' and output port to ``RS232C.''

The 11801A's Hardcopy Parameters menu is shown in the following image, which
was captured with tekdump, of course.

Select the ``GPIB/RS232C'' menu item, and make sure that the RS232 parameters
are set as follows. Baud rate should be 19200, parity is none, echo is off, stop
bits set to 1, ``flagging'' is soft, delay is 0, ``EOL String'' is LF/CR,
``verbose'' is off, and ``RS232C Debug'' should be off. Don't mess with the GPIB
settings.

The setup screens for the DSA602 are almost identical, except that there are
three pages of utility menu items; after pressing the Utility button, touch the
``Page to Utility N'' item until the RS-232 and Hardcopy menu items appear.

Host computer.

Tekdump was developed on a pentium pro PC running Linux kernel 2.0.23. It
compiles and the -f option
works fine under HP-UX 10.20, but has never been tested with the scope connected
directly to an HP. It should be easily portable to any POSIX compilant version
of Unix with an ANSI C compiler.

FILES

/dev/cua0 - default serial port for communicating with the
scope, at least under Linux.

SEE ALSO

ppm(1), pnmtotiff(1), ppmtogif(1), tty(4)

Tektronix 11801A Digital Sampling Oscilliscope User Manual, page 115
``hardcopy'' and page 191, ``RS232-C Parameters.''

CAVEATS

There is no convenient way to capture the raw output from the scope in a file
for later processing with tekdump's -f
option.

Errors in serial data have been observed when tekdump's output is directed to
the local disk on a Dell Optiplex-pro GX running a 2.0.23 kernel. These are
indicated by occaisional ``bad character'' and ``incorrect line length'' error
messages and by horizontal streaks in the output image. No such problems have
been observed when directing the output to an NFS-mounted partition.

The oscilloscope puts an informational banner on the screen when each screen
image has finished tranmission to the host. The hardcop function dumps the exact
screen image, so if the hardcopy button is pressed again at this time, the next
screendump will include this ``Hardcopy is complete'' banner. To clear the
message, press any of the front panel buttons, for example ``Waveform.''

BUGS

The -B option
doesn't work yet. When implemented, it will require the use of hardware flow
control, which on the 11801A requires a nonstandard cable.

The 11801A's serial port only goes up to 19,200bps.

The 11801A is nice enough to send its idea of the date and time of the
screendump, but there's really nothing useful that tekdump can do with this
information.

AUTHOR

Steve Tell, [email-masked]