Hi Carl, I have a BeagleBone Black up and running with wheezy, LXDE desktop and Gambas 3.5.9 I am able to use all most all of the available GPIO and read the AD's using Gambas, I have not had any uarts up. I see no problem in getting the the uarts to run using standard USB to serial converters (Jaycar) work well with the Rpi.
I also have Rpi series B running with the same OS & desktop as the BBB and using Gambas 3. This is connected to an Arduino Uno via a usb uart on the Rpi used to control 6 signals and 7 point motors on a miniature railway all running at 56000 baud. Using an input from the terminal the Gambas software sends an ASCII message via the uart to the Uno and it will execute the request (change points or signals) and send back an ASCII message the request was executed. This is not a very high speed system as changes may be seconds or minutes. I have also used Gambas to communicate with PLC's using Modbus RTU and crc16 at 9600 baud with high volume short interval requests over RS485 networks and up to 20 nodes. The secret was to use a PC, PLC or RTU as the master and use a timer to set the pole rate from the master. I have also as you used VB6 to implement an extensive SCADA system for small power house control. This was a very high volume data through put and I did not find the need to use any special data handling to free up the PC. The PC was off doing a lot of other stuff while the SCADA was running. I have implemented a small test SCADA module in Gambas and see no problems with speed compared to commercial SCADA packages even when using the DNP3 protocol. The through put with VB6 or Gambas seemed to be about double compared to commercial solutions. I would say I have had best results using an interrupt driven serial routine to empty the uart buffers and handle the data. VB6 using OnComm() function and Gambas using Sport_Read() function. Variable buffer sizes can be dealt with by checking the length of the input string using CR as the end of line indicator (chr13) as used in most protocols (modbus ASCII & RTU). Try something like, Try Print #Sport, Tx; Chr$(13) in a timer function or from terminal input to send data through the uart. If needed I have the Gambas modbus test program and a Koyo Click PLC (under $100 au PLC software is free) to test and see if the code is still OK, the modbus protocol uses binary data over the comms link. Hope this is of some help. Best Regards Mike Merry Christmas to all. On Tuesday, 24 December 2013 2:38 AM, Carl Nilsson <nils...@iinet.net.au> wrote: G'day Guys (Nando, Randall and Mike): Thanks for your helpful replies. It's 5 am here and I woke up an hour ago with this matter running through my head, so your replies are welcome! All good advice. I realized that, first of all, I needed to get a handle on using the stream functions, which are quite new to me. Secondly, as usual, there are many ways to skin a cat. You are right, I need not be dependent on an RThreshold property. I have been using this for years most successfully with MScomm in VB6. It does exert efficient control, but sometimes my incoming packets vary in byte count.. So, early in the piece, I wrote code that would look for any remainder bytes or shortfall on the end of the designated input stream and put them onto the start of the next byte block to get back into synch. The Windows kernel has a very efficient function called "MoveMemory" that can be called from VB6. (I presume Linux has something similar). It's very much faster than shifting bytes in Do loops. Anyway, not being dependent on an totally accurate byte count prior to triggering an event suggested an alternate approach: My principal data device is a decade-old Microstrain Inertial Management Unit (IMU).that sends remorselessly at around 2356 bytes (sometimes plus a packet or two) per sec. At the moment I'm doing all my processing on an old Advantech 9576F single board computer running Win 2K. With about 8 serial ports in action and heaps of other processing to do, I wanted to ease things with some preprocessing of some data streams on one of these little new ARM boards like the Raspberry Pi or Beaglebone Black - the latter with at least 4 UARTS and running at 1 GHz seems very attractive. They can run fully embedded under Linux with gambas for initial data processing. I have an RPi now with gambas3 and wiring Pi installed to experiment with. Sometimes the IMU traffic is duplex when I change parameters in flight and additional data packets come back in addition to the normal data flow. So I adjust the RThreshold value dynamically, but that's not vital. All this adds up to the fact that another approach might be to trigger processing events simply with a timer - read the full stream each time and get the byte count approximately right. With a "MoveMemory" function I can easily handle some unevenness in byte count. As I said, I'm looking for the least drain on CPU load. I don't really need the system tied up waiting and testing for an exact count. Anyway, I thank you for all your comments. I now know that what I need can be done and the next step is for me to experiment. Yesterday I was having some doubts about choosing gambas. Nice to talk with you guys. I'll get back to you when I have something more useful to say or ask. Merry Christmas, Carl At 08:03 PM 23/12/2013, you wrote: >My suggestion to reading 124 bytes from a serial stream.... > >I use this technique mostly because I want to empty the buffer >provided by the control >as much as possible. > >I would have one function which is the _read of the serial port. >The only thing it does is accumulate bytes in an array. > >I have another function which will ask for 124 bytes from the >accumlating array. >If there are not enough, it can block, or return an array of zero long >which would mean not enough came in. >In this case you could also do a small time delay (ie. WAIT 0.1) >just to prevent the CPU from running 100% testing for 124 bytes. > > >Both of these can be a Gambas Class and the second function is the >public function. >You can use _new to instantiate the serial port control. >You don't need to create it at design time. > >I used techniques like this and it works like a charm. >-Nando > > >---------- Original Message ----------- >From: Randall Morgan <rmorga...@gmail.com> >To: mailing list for gambas users <gambas-user@lists.sourceforge.net> >Sent: Sun, 22 Dec 2013 23:35:33 -0800 >Subject: Re: [Gambas-user] Serial port control > > > I think the RTheshold of VB simply sets the byte count that must accumulate > > in the receive buffer before a comm event is triggered. It doesn't do > > anything else. In the background VB is still polling the buffer and looking > > at the byte count. You can do this in GB but you will have to write it > > yourself. You would need to simply use the read event on the comm object to > > test the byte count. I believe it triggers at 1 byte. Then use that to > > trigger your own custom event when your 124 bytes have arrived. > > > > You might also be able to talk Benoit into adding an RThreshold property. > > Seems like it might be handy.... At the very least 4Hz is very very slow > > for most computers. And setting up a 4Hz polling of the port wouldn't be > > hard at all. > > > > On Sun, Dec 22, 2013 at 8:10 PM, Carl Nilsson <nils...@iinet.net.au> wrote: > > > > > Thanks Randall. I guess it's time to try it and play around a > > > little, which I can't do for a few days. At the moment I'm trying to > > > look ahead and see where problems might lie. (snip) Carl S Nilsson 137 Gordons Hill Road Lindisfarne, Tas. Australia 7015 ------------------------------------------------------------------------------ Rapidly troubleshoot problems before they affect your business. Most IT organizations don't have a clear picture of how application performance affects their revenue. With AppDynamics, you get 100% visibility into your Java,.NET, & PHP application. Start your 15-day FREE TRIAL of AppDynamics Pro! http://pubads.g.doubleclick.net/gampad/clk?id=84349831&iu=/4140/ostg.clktrk _______________________________________________ Gambas-user mailing list Gambas-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/gambas-user ------------------------------------------------------------------------------ Rapidly troubleshoot problems before they affect your business. Most IT organizations don't have a clear picture of how application performance affects their revenue. With AppDynamics, you get 100% visibility into your Java,.NET, & PHP application. Start your 15-day FREE TRIAL of AppDynamics Pro! http://pubads.g.doubleclick.net/gampad/clk?id=84349831&iu=/4140/ostg.clktrk _______________________________________________ Gambas-user mailing list Gambas-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/gambas-user
