I have a program written in Visual Basic (.NET Framework 3.0) that communicates with a power supply via a D2XX driver (over COM3) and a pump via a VCP driver (over COM2). Currently, if both USB devices are plugged in when I start the program, it tries to communicate with the pump, (COM2) when trying to communicate with the power supply (COM3). I found a temporary solution to this issue by only have the power supply connected when starting the program. Then I initialize communication with the power supply, and afterwards plug in the pump; this allows the program to communicate with both separately for the rest of the time running the program. But this process is tedious and I am hoping there is an alternative solution where I can keep both units connected via USB and the computer communicates separately. What is confusing is that this communication issue was not always the case, a week ago it worked without having to disconnect the pump (all drivers are updated, and on the device manager they are listed as their respective COM ports as well) ; I am struggling to find some correlation between what is the underlying issue.
I tried to delete other hidden additional COM ports. I made sure all drivers were updated. When the pump is communicating via the same port as the power supply, and then I try to communicate with the pump, I receive this error:
System.UnauthorizedAccessException
HResult=0x80070005
Message=Access to the port 'COM2' is denied.
Source=<Cannot evaluate the exception source>
StackTrace:
<Cannot evaluate the exception stack trace>
But again, If I start the program with only the power supply plugged in and initialize communication with the power supply, and THEN plug in the pump, this issue is evaded. I hope someone can give some sort of direction at all troubleshooting this issue because I am completely stumped. Thank you!
Most likely your program implicitly relied on the correct enumeration order. If you use devices with an FTDI product with internal flash or with dedicated eeprom, you may be lucky: Many can configured via FT_PROG to be visible only for D2XX and not as VCP. This way you can avoid the problem. Alternatively, you can try to modify your program so that it accesses D2XX first. Make sure to filter out the correct device using device informations. E.g. the serial number or the VID:PID if the device manufacturer has made the effort to aquire its own IDs. Check 3.4 FT_GetDeviceInfoList of D2XX Programmer's Guide for details.
I'm playing around with an old Trackball I purchased from Sparkfun. My trackball powers on, but it doesn't actually work. All the lights flash, and it indicates that I've left and right clicked, but the mouse on my screen does nothing.
I want to monitor the input values of the trackball across a USB port so I can track down the problem. I've looked for code I can run on Netbeans, but came up empty handed.
Please advise
You didn't specified what OS are you using. You need dedicated driver for this device. In case of Linux you would need to write your own driver for the kernel. But first you need to have specification of protocol which this device is using over usb and also usb protocol itself. It is quite sophisticated task to do...
In case of Windows there are some programs for dumping transmission between usb host (PC) and device (trackball), but at the moment I can't give you any name of such program. In case of Linux you can dump the transmission using tcpdump or wireshark commands.
I'm trying to build a device to read the current GPS coordinates. The device will include a small computer inside running Windows 7.
I'm looking for a usb GPS to connect it to the computer and be able to read the GPS coordinates from my VB.net 2010 program. Of course, here the most important thing is what hardware I need to accomplish that. Suggest me some GPS models.
Do I need only a GPS receptor or do I need even more hardware?
In addition to jcibar's answer:
For Bluetooth GPS or most USB devices you probably don't even have to set the classic RS232 communication settings like "baud rate". It will just work, whatever baud rate you set.
Look at the "Ports (COM & LPT)" list of the Windows Device Manager - One of the "COM" devices listed should be the GPS receiver and it many times includes a description that indicates what it is.
E.g. on my Win7 x64 notebook I have a "Sierra Wireless Gobi 2000 HS-USB NMEA 9001 (COM8)" port, which is the notebook's built-in GPS. It will just start communicating the moment I open the port:
17.09.2013 10:12:01.890 [RX] - $GPGSA,A,1,,,,,,,,,,,,,,,*1E<CR><LF>
$GPGSV,4,1,16,10,,,,21,,,,20,,,,32,,,*7A<CR><LF>
$GPGSV,4,2,16,31,,,,30,,,,29,,,,28,,,*78<CR><LF>
$GPGSV,4,3,16,27,,,,26,,,,25,,,,24,,,*79<CR><LF>
$GPGSV,4,4,16,23,,,,22,,,,19,,,,18,,,*7E<CR><LF>
$GPGGA,,,,,,0,,,,,,,,*66<CR><LF>
$PQXFI,,,,,,,,,,*56<CR><LF>
$GPVTG,,T,,M,,N,,K,N*2C<CR><LF>
$GPRMC,,V,,,,,,,,,,N*53<CR><LF>
You can use any serial COM port / RS232 logger to test this.
You can use any GPS (USB, Bluetooth) that provides a RS232-level serial interface (serial port). The GPS will create a virtual serial port (e.g. COM13) that you can use in your VB.net program to read serial data (NMEA frames tipically at 4800 bauds).
For instance, for USB you could use something like this: Haicom HI-206USB.
I'm running some code on Arduino, I have website with a slider which uses a cgi script to pass values to Python. Then the python script uses pySerial to send the values to Arduino which controls a motor.
The plan was to be able to control the motor speed using the slider on the website.
However I seem to be coming up against a problem of the Arduino resetting whenever I change a value on the website, causing the motor to stop. Is there any way around this? My python code is below.
#!/usr/bin/env python
import cgi
form=cgi.FieldStorage()
import json
ser = serial.Serial('dev/ttyACM0', 9600)
#I think there should be a sleep here for 1.5 seconds
ser.write("%s\n" % (form["value"]))
ser.close()
print "Content-type: application/json"
print
print(json.JSONEncoder().encode({"status":"ok"}))
So, say I have the motor running at 50% speed, then change a value on the website, it runs this script which executes the serial.Serial('dev/ttyACM0', 9600) command. That opens the port which resets the arduino, stopping the motor before passing the new command.
Is there any way to pass ser.write("%s\n" % (form["value"])) to the arduino without freshly opening the port? Such as leaving the port open between python sessions?
If not, is there any other way around this problem?
I believe the reset is due to a hardware design of the specific Arduino device you are using. I suggest using an Arduino Micro or Leonardo board instead. They use a virtual serial port and should not restart your sketch each time a serial port is opened. This is from the Arduino site:
No reset when you open the serial port.
Unlike the Arduino Uno, the Leonardo and Micro won't restart your
sketch when you open a serial port on the computer. That means you
won't see serial data that's already been sent to the computer by the
board, including, for example, most data sent in the setup() function.
Serial re-enumeration on reset.
Since the boards do not have a dedicated chip to handle serial
communication, it means that the serial port is virtual -- it's a
software routine, both on your operating system, and on the board
itself. Just as your computer creates an instance of the serial port
driver when you plug in any Arduino, the Leonardo/Micro creates a
serial instance whenever it runs its bootloader. The board is an
instance of USB's Connected Device Class (CDC) driver. This means that
every time you reset the board, the USB serial connection will be
broken and re-established. The board will disappear from the list of
serial ports, and the list will re-enumerate. Any program that has an
open serial connection to the Leonardo will lose its connection. This
is in contrast to the Arduino Uno, with which you can reset the main
processor (the ATmega328P) without closing the USB connection (which
is maintained by the secondary ATmega8U2 or ATmega16U2 processor).
This difference has implications for driver installation, uploading,
and communication...
I you might be able to use the setDTR(False), but I have tested this yet. A while back they fixed the bug that were initially associated with setDTR. What operating system are you use this on?
ser = serial.Serial('dev/ttyACM0', 9600)
ser.timeout = 1
ser.setDTR(False)
Let us know if this does not work.
Follow on from - GPS Intermediate Driver Issues
The above was not successfully answered and feel I have new information over the issue to go for a new question.
The issue I am facing is the speed of which data is being delivered by the GPS Intermediate Driver.
I have successfully used Pocket Putty to read the serial ports and see the exact information been exposed.
COM 1 - GPS Intermediate Driver
COM 6 - Serial port to PC (Input data manually)
COM 8 - Virtual serial port for GPS hardware.
When reading COM 8, I can see about 18 NMEA strings appear every ~3 seconds, this is as fast as we can push it over the limited USB connection. And it appears quickly on the display. When reading COM 6 (send data from PC manually), it is displayed equally as quick. So there is no problem with the data been available.
Enter in the GPS Intermediate Driver. When The GPS Intermediate Driver is set to COM1 (Software) and COM6 (Hardware). The data entered on COM6 is displayed on COM1 just as quickly as it was without the GPS Intermediate Driver. The data is unaltered, so if I send "JON" on COM6, it will appear on COM1, even though its not valid NMEA data, which is fine.
The problem is with COM8. When the GPS Intermediate Driver is set to COM1 (Software) and COM8 (Hardware). The data showing in PocketPutty on COM1 is really slow. The output on the screen is about 5 characters per second, the data is valid but it just been delivered very slowly. This to me points out an issue in the implementation of the virtual serial port, as if the GPS Intermediate Driver is not reading all the data just one character at a time, given I have isolated the issue to my virtual serial port.
Can anyone provide a clear example of a virtual serial port implementation, as im not sure what I could change to improve this, given COM8 directly works with GPS software and the PocketPutty application, which indicates the data is available, being read, and is correct.
After getting support from the device manufacturer running a debug build, the cause of the problem was client applications were making to many read calls. The serial port could handle them on its own, but via the GPS Intermediate driver the number of calls were too high and the overhead was crippling the communication, this was down to Mutex locks and general threading issues.
Client applications need to read 960 bytes of data per read to the GPS Intermediate driver for them to work ok. This is not an ideal solution so another fix was found.
The resolution was to add in a WaitForSingleObject(IsThereEnoughGPSDATAEvent, COMTotalTimeout) in the read method, so that all reads would only get data if there was a sufficient amount of data available. Originally I requested 960 to be available in the buffer but i've set it down to just 10 bytes and it still works.
Sample Code
DWORD COM_Read( DWORD hOpenContext, LPVOID pBuffer, DWORD Count )
{
if(gpsThreadEvents[GPS_THREAD_EVENT_DATA_AVAILABLE] != NULL)
{
if(WaitForSingleObject(gpsThreadEvents[GPS_THREAD_EVENT_DATA_AVAILABLE], GPSTimeouts.ReadTotalTimeoutConstant) != WAIT_OBJECT_0)
{
return 0;
}
}
//read code goes in here
return dataOut;
}