Solved

Serial Communications Emulation with Software

Posted on 2013-05-28
6
389 Views
Last Modified: 2013-06-13
I need to emulate a Symbol PDT Gun communicating with an application over a serial line.  I have monitored the communication between the devices and found the the device sends 0x"32", 0x"32", 0x"2d", 0x"ff", 0x"ff" before it receives a response from the application.  When I send this character stream from a program on a different computer, I get no response.  Any suggestions on what I may be missing?  The normal device wiring configuration has CTS wired to RTS (pins 7 to 8) and DTR is grounded (pins 4 to 5).
0
Comment
Question by:ceepaulw
  • 3
  • 3
6 Comments
 
LVL 83

Expert Comment

by:Dave Baldwin
ID: 39202753
DTR may be grounded on your device but that would be very unusual for a computer because it shorts on the line driving it on the other end.  For computer to computer, try the "RS232 null modem with full handshaking" on this page: http://www.lammertbies.nl/comm/cable/RS-232.html
0
 

Author Comment

by:ceepaulw
ID: 39206473
Thank you, that was a lot to read.  Maybe I've gotten ahead of myself.  I have a computer talking with a bar coded reader.  The device is defined as a printer in the computer.  I want to replace the bar  code reader with a computer program.  I have intercepted the data transfer and have replaced it in a program but when I send the first packet, there is no response. I am trying to set up CTS and RTS as well as DTR combination with no luck.  What I tried to describe above was what the original wiring had-it had a DE9 connector on one end and a DB25 on the other.

How can I figure out how to interface with the hardware on the computer as some sort of hardware interaction must be taking place Out-of-Band.  One person suggested that I need a circuit board to accomplish this.

Thanks.
0
 
LVL 83

Expert Comment

by:Dave Baldwin
ID: 39206575
I don't know what you mean by "Out-of-Band".  I do know that Windows serial port drivers implement handshaking to control both sending and receiving.  In Device Manager, you can right-click on your 'Communications Port' and select Properties.  On the Port Setting tab, you can set the default values for that port.  That would be for setting up another computer to talk to the one that the bar code reader was attached to.

Now if you are talking about replacing the bar code reader with a program on the Same computer, then you have to intercept the calls to that serial port which is much more difficult.
0
Superior storage. Superior surveillance.

WD Purple drives are built for 24/7, always-on, high-definition security systems. With support for up to 8 hard drives and 32 cameras, WD Purple drives are optimized for surveillance.

 

Accepted Solution

by:
ceepaulw earned 0 total points
ID: 39231524
I found a program "com0com" that enabled me to easily try different combinations of dtr, dsr, etc.  Once the right signals were wired or shorted, the computer responded to the data from the other computer.  By out-of-band I was referring to signalling not visible in the data recorder.
0
 

Author Closing Comment

by:ceepaulw
ID: 39243846
I spent considerable time to also search for solutions in other areas.  One of these panned out.
0
 
LVL 83

Expert Comment

by:Dave Baldwin
ID: 39245294
0

Featured Post

Is Your Active Directory as Secure as You Think?

More than 75% of all records are compromised because of the loss or theft of a privileged credential. Experts have been exploring Active Directory infrastructure to identify key threats and establish best practices for keeping data safe. Attend this month’s webinar to learn more.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

In this article we have discussed the manual scenarios to recover data from Windows 10 through some backup and recovery tools which are offered by it.
What do we know about Legacy Video Conferencing? - Full IT support needed! - Complicated systems at outrageous prices! - Intense training required! Highfive believes we need to embrace a new alternative.
This is used to tweak the memory usage for your computer, it is used for servers more so than workstations but just be careful editing registry settings as it may cause irreversible results. I hold no responsibility for anything you do to the regist…
Hi friends,  in this video  I'll show you how new windows 10 user can learn the using of windows 10. Thank you.

911 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question

Need Help in Real-Time?

Connect with top rated Experts

20 Experts available now in Live!

Get 1:1 Help Now