On Wed, 22 Sep 1999, Vern Hoxie wrote:
>
> On Wed, 22 Sep 1999, Rudy Moore wrote:
>
> > I'd like to be able to look at the data transmitted between a
> > program running under linux (vmware) and the object it's talking
> > to (a garmin GPS). Ideally, I'd like to snoop the TX and RX lines
> > and save it to a file to look at later. Any suggestions on how
> > I can do this?
>
> This is an application problem and requires an application solution.
>
> That is, modify your application program to write the information to a
> file(s) as it is sent to the driver and as it is received.
>
I don't think so myself.
Unless you actually modified the application to check the
status of the serial line for incoming characters
frequently it would probably be better to use an
external monitor.
quite a while ago (1988) I bought a program
that ran under dos and used 2 serial ports
to capture and record the data from both tx and rx lines.
this program was called DLM
check out
http://www.dunfield.com/dlm.htm
I think this is the same program
DLM
Data Line Monitor. Turns your P.C. into a
DATASCOPE.
This program monitors both sides of an asynchronous data
communications line using a passive "Y" cable which
connects to the monitored devices and BOTH comm ports
(COM1 and COM2). This tool is invaluable for debugging ANY
asynchronous connection, such as TERMINALS, MODEMS, SERIAL
PRINTERS and PROTOCOL debugging. It allows you to actually
SEE the data and signals being passed between the devices.
Easy to use menu driven interface.
"Split Line" display for easy viewing of the
interaction between two devices. Display is updated
in "real time".
Over 50 screens may be "buffered" and reviewed
later.
Displays/Stores hardware signal information as well
as all data passed between the devices.
Captured buffers may be saved to disk for later
reference.
Includes directions for constructing your own "Y"
cable.
Software price : $29.95 US
I found a 'demo' version at
http://grantronics.com.au/micro-c.html#dlm
in the zip file there was documentation for creating the "Y" cable:
2.2 Passive Monitor Cable
DLM monitors DTE data on COM1, and DCE data on COM2. Therefore,
you must connect the input (DCE) lines from COM1 to the DTE origin
signals on the monitored line, and the input (DCE) lines from COM2
to the DCE origin signals.
To do this, you must construct a "Y" adapter cable, which
contains a set of "straight through" connectors which are inserted
in the RS-232 line being monitored, and also connects the DTE and
DCE signals to the appropriate input (DCE) pins on COM1 and COM2.
Be sure to mark which COMM port each of the two "PC" connectors
connects to. If you get them backwards, the DTE/DCE data and
signals will appear reversed.
"Straight through" "IBM PC"
Line Monitor Connector COMM port connectors
DB-25 Male /----- COM1 (Monitor DTE)
| | | | | | | /
+-+-+-+-+-+-+==================<
| | | | | | | \
DB-25 Female \----- COM2 (Monitor DCE)
The signals must be connected as follows:
Line Pin Port 25-Pin(PC) 9-Pin(AT)
-------------------------------------------------
TXD 2 ---- COM1 3 2
RXD 3 ---- COM2 3 2
RTS 4 ---- COM1 5 8
CTS 5 ---- COM2 5 8
DSR 6 ---- COM2 6 6
GND 7 ---- COM1+COM2 7 5
DCD 8 ---- COM1 22 9
DTR 20 ---- COM1 6 6
RI 22 ---- COM2 22 9
Aux 1* - ---- COM1 8 1
Aux 2* - ---- COM2 8 1
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