473,692 Members | 2,160 Online
Bytes | Software Development & Data Engineering Community
+ Post

Home Posts Topics Members FAQ

how to send command to serial ports in C++

5 New Member
Hi,

I'm really new to C++. I'd like to know how to send command to serial ports.
Im connecting to a uniwell POS machine and I dont know what commands I'll be using. They gave me this serial communication protocol manual with this format.


1.4 Clear All Request

It is always safest to clear all existing report requests before you request the days reports. This is done by sending the following request.

SOH C - A STX 0 1 CR LF ETX BCC


how do you send commands like that to a serial port?
Thank you.
Mar 11 '09 #1
9 13167
newb16
687 Contributor
On windows, open file handle with command like
HANDLE serialhCom = CreateFileA(dev name, GENERIC_READ | GENERIC_WRITE, 0, NULL, OPEN_EXISTING, FILE_FLAG_OVERL APPED, NULL);
Then write to it using WriteFile().
On other OS it will differ, it depends on OS more that on language.
Mar 11 '09 #2
Cerebro
5 New Member
hi newb16.

Thanks for the reply.

Yes i've done the connection part and other stuff.. My concern is how to pass that particular command to a serial port. I know it would be using the WriteFile command..


Shall I do it this way?

char strCmd[] = {'S','O','H','F ','-','R','S','T',' X','0','1','C', 'R','L','F','E' ,'T','X','B','C ','C'};

or in hexadecimal format?

char strCmd[] = {0x01,0x46,0x2D ,0x52,0x53,0x54 ,0x58,0x00,0x01 ,0x0D,0x0A,0x03 };


and ive called this function:

BOOL bWriteCmd = objCom->sendData(strCm d,sizeof(strCmd ));

//where sendData() function is declared as member of a class:

DWORD comport::sendDa ta (const char* data, DWORD size)
{
DWORD numberOfBytesWr itten;

WriteFile(_hCom ,
data,
size,
&numberOfBytesW ritten,
0);

return numberOfBytesWr itten;
}

and I've tried to get the machine's reply by calling this function:

DWORD comport::receiv eData (char* data, DWORD size)
{
DWORD numberOfBytesRe ad;

ReadFile(_hCom,
data,
size,
&numberOfBytesR ead,
0);

return numberOfBytesRe ad;
}

coz i've done both strCmd declaration and I haven't received a reply from the pos machine.
Please help. Thank you.
Mar 11 '09 #3
gpraghuram
1,275 Recognized Expert Top Contributor
HI,
U need not convert the command to hexadecimal format and send it.
If you do like that then in the receiving box you have to reconvert it back and execute the command.
So send the command as a string and after reading the command execute it on the other box.

Raghu
Mar 11 '09 #4
Cerebro
5 New Member
Hi Raghu,

Thanks for the reply. I've tried it just now... but still not working. Is there a way that maybe I could get a reply just so I would be sure that I am really transfering a command to the machine? maybe a generic command that would get the machine's address, name.. etc.
Mar 12 '09 #5
gpraghuram
1,275 Recognized Expert Top Contributor
Can you explain in which part u r having issue?
Issue is in the receiving part or in execution of the received command?

raghu
Mar 12 '09 #6
JosAH
11,448 Recognized Expert MVP
@Cerebro
In ASCII SOH means 'Start Of Heading' (code 0x01) and STX means 'Start of TeXt' (code 0x02), CR means 'Carriage Return' (code 0x0D), LF means 'Line Feed' (code 0x0A), ETX means "End of TeXt' (code 0x03) but I don't know what the BCC means or how to interpret C - A. Check your manual

kind regards,

Jos
Mar 12 '09 #7
Cerebro
5 New Member
@gpraghuram
hi,


issue is I can't get the machine to respond to my command. It might be that the machine does not understand my command, which is why I was asking how to send the command to serial port, or I'm lost here. I'll read tutorials on the net. Thank you for the response.
Mar 13 '09 #8
Cerebro
5 New Member
@JosAH

Hi Jos,

Yes i know what that means, that's why I was asking how to send those commands to a serial ports..by hex or by string.. coz I still can't get the machine to reply to me.

Thank you for your reply.
Mar 13 '09 #9
JosAH
11,448 Recognized Expert MVP
@Cerebro
What I saw from your reply #3 is that you were trying to send the symbolic names of the commands; that's not how you do it; if you have to send:

SOH C - A STX 0 1 CR LF ETX BCC

... you actually have to send the byte values

0x01 'C' '-' 'A' 0x01 '0' '1' 0x0d 0x0a 0x02 'B' 'C' 'C'

I'm not sure about that C - A part and the BCC part, check your manual.

kind regards,

Jos
Mar 13 '09 #10

Sign in to post your reply or Sign up for a free account.

Similar topics

4
7458
by: M. Raab | last post by:
i have written an application that utilizes serail ports. In order not to have to reinvent code, I decided to use John Hind's sample code that he presented in MSDN magazine last year (Serial Comm: Use P/Invoke to Develop a ..NET Base Class Library for Serial Device Communications John Hind - MSDN Magazine - October 2002) it works fine except for one problem. i cannot address any port higher than COM9. I am using an equinox multi-serial...
13
4818
by: Al the programmer | last post by:
I need to access the serial ports on my webserver from an asp.net page. I have no problem accessing the serial ports from a windows form application, but the code doesn't work in asp.net. I have been told it is not possible to access the serial ports from asp.net. The application is used to control custom hardware. The hardware is connected to a PC through serial ports. Our customer wants to control the hardware from a remote...
1
1758
by: David | last post by:
I have written an application in VB.NET 2003 that uses the SAX serial component for RS232 communications with hardware. The program sets up 2 serial ports so that it can talk to 2 different hardware devices simultaneaously. When I run the program on a desktop running Windows 2000 it works fine. When I run it on a Laptop using XP I start having problems. It seems that when the ports are initiated, either one will work but not the
3
2988
by: Tom Brown | last post by:
Hey people, I've written a python app that r/w eight serial ports to control eight devices using eight threads. This all works very nicely in Linux. I even put a GUI on it using PyQt4. Still works nicely. Then I put the app on on a virtual Windows machine running inside of vmware on the same Linux box. Vmware only lets me have four serial ports so I run the app against four serial ports using four threads. The app did not respond...
5
9490
by: LongBow | last post by:
Hello, Is there a way, in .NET, to determine what are the avialable Serial (Communications) Ports on a Windows OS and is there a way to determine that port isn't being use other than attempting to opening the Serial Port and catching the associated exception? Thanks If there isn't a way to determine the Serial Port within .NET I would be willing, I guess, to use a WinAPI is that was the only way.
2
3954
by: joaquimfpinto | last post by:
Dear All, I made an app in c# that uses several serial ports. For the serial ports I use a pnp Sunix board, some with 8 serial ports other with 4 or even 2 serial ports. Whenever I use the development computer I don't have ay problem with my application.
2
4310
by: pauland80 | last post by:
Hello, My soft passively listen to a device sending +- 300 bytes of data each second. After several hours of work, the soft abruptly stops receiving data without any error, (while the device sends properly, of course) and I need to restart it (the python soft) to "reactivate" the ports. I read that when the serial port encounters an error (frame error or so, I imagine?) it stop receiving data until the library function...
3
11608
by: naveen.sabapathy | last post by:
Hi, I am trying to use virtual serial ports to develop/test my serial communication program. Running in to trouble... I am using com0com to create the virtual ports. The virtual ports seem to be working fine when I test it with Hyperterminal . I am using the example program that comes with pyserial, as below. --------------- import serial
2
7826
by: Nasif | last post by:
Currently I am writing a program which sends and receives messages through serial port to a device. I am using C# and Microsoft Visual studio 2005 for windows program. But my problem is when i try to write in serial port from my windows a Timeoutexception is thrown. I use SerialPort class in System.IO.Ports and for writing port i used write() function under the built in class SerialPort. But when i use hyperterminal , everything goes fine....
0
8545
by: Hystou | last post by:
Most computers default to English, but sometimes we require a different language, especially when relocating. Forgot to request a specific language before your computer shipped? No problem! You can effortlessly switch the default language on Windows 10 without reinstalling. I'll walk you through it. First, let's disable language synchronization. With a Microsoft account, language settings sync across devices. To prevent any complications,...
0
9090
Oralloy
by: Oralloy | last post by:
Hello folks, I am unable to find appropriate documentation on the type promotion of bit-fields when using the generalised comparison operator "<=>". The problem is that using the GNU compilers, it seems that the internal comparison operator "<=>" tries to promote arguments from unsigned to signed. This is as boiled down as I can make it. Here is my compilation command: g++-12 -std=c++20 -Wnarrowing bit_field.cpp Here is the code in...
1
8810
by: Hystou | last post by:
Overview: Windows 11 and 10 have less user interface control over operating system update behaviour than previous versions of Windows. In Windows 11 and 10, there is no way to turn off the Windows Update option using the Control Panel or Settings app; it automatically checks for updates and installs any it finds, whether you like it or not. For most users, this new feature is actually very convenient. If you want to control the update process,...
0
8810
tracyyun
by: tracyyun | last post by:
Dear forum friends, With the development of smart home technology, a variety of wireless communication protocols have appeared on the market, such as Zigbee, Z-Wave, Wi-Fi, Bluetooth, etc. Each protocol has its own unique characteristics and advantages, but as a user who is planning to build a smart home system, I am a bit confused by the choice of these technologies. I'm particularly interested in Zigbee because I've heard it does some...
1
6462
isladogs
by: isladogs | last post by:
The next Access Europe User Group meeting will be on Wednesday 1 May 2024 starting at 18:00 UK time (6PM UTC+1) and finishing by 19:30 (7.30PM). In this session, we are pleased to welcome a new presenter, Adolph Dupré who will be discussing some powerful techniques for using class modules. He will explain when you may want to use classes instead of User Defined Types (UDT). For example, to manage the data in unbound forms. Adolph will...
0
5822
by: conductexam | last post by:
I have .net C# application in which I am extracting data from word file and save it in database particularly. To store word all data as it is I am converting the whole word file firstly in HTML and then checking html paragraph one by one. At the time of converting from word file to html my equations which are in the word document file was convert into image. Globals.ThisAddIn.Application.ActiveDocument.Select();...
0
4327
by: TSSRALBI | last post by:
Hello I'm a network technician in training and I need your help. I am currently learning how to create and manage the different types of VPNs and I have a question about LAN-to-LAN VPNs. The last exercise I practiced was to create a LAN-to-LAN VPN between two Pfsense firewalls, by using IPSEC protocols. I succeeded, with both firewalls in the same network. But I'm wondering if it's possible to do the same thing, with 2 Pfsense firewalls...
0
4562
by: adsilva | last post by:
A Windows Forms form does not have the event Unload, like VB6. What one acts like?
1
2978
by: 6302768590 | last post by:
Hai team i want code for transfer the data from one system to another through IP address by using C# our system has to for every 5mins then we have to update the data what the data is updated we have to send another system

By using Bytes.com and it's services, you agree to our Privacy Policy and Terms of Use.

To disable or enable advertisements and analytics tracking please visit the manage ads & tracking page.