serial comms BS2 to VB app

realolman

I am communicating with a·BS2 from a VB express app using

Seconds VAR Word 
Comms VAR Byte 

LookComm: 
SERIN 16, 16780,500,Counting, [noparse][[/noparse]Comms] 
 

Counting: 

PAUSE 500 

 IF Comms <> 0 THEN 

  SEROUT 16, 16780, [noparse][[/noparse]DEC4 Seconds] 
  Comms =0 

 ENDIF 

Seconds = Seconds+1 

GOTO LookComm: 
 


END

in the BS2

and

·······
·······

SerialPort1.Write("*") 

to send a * character to the BS2 from the VB app·telling it that I want it to·send the value of "Seconds" ·to my app· ...

and using

txtSerialPort.Text = SerialPort1.ReadExisting

to read the BS2 response. I always get the * that I sent to the BS2 as part of txtSerialPort.Text

I don't think the BS2 is doing it , but I don't know.


·I have tried

VB

txtSerialPort.Text = SerialPort1.ReadExisting

again right after writing the star, because it seems that "empties " the buffer after a read... If I read it twice I get nothing on the second try., but it doesn't make any difference right after the write...
·I've tried VB

DiscardOutBuffer

and VB

DiscardInBuffer

but it doesn't seem to help
I suppose I could use some technique in the VB app to strip off the *, but I would llike to make it quit doing that and understand why it's doing it.

Would the BS2 be doing it?

Unsoundcode

Hi realolman,·anything you write to the BS2 is echoed back and captured by the input buffer of the serial port. Bytes remain in the buffer until they are read somehow. What you need to do is remove the echo before reading your data. There are several ways you can do that, one way that is fairly secure is to have the Stamp send a header before the data and have the PC app read but ignore everything that precedes the header. I also like to use SerialPort1.ReadLine and have the Stamp transmit a newline or carriage return to signal the end of the data.

BS2...........SEROUT tx,baud,[noparse][[/noparse]"!",10,DEC4 seconds,10]

VB......

Do

in_string=SerialPort1.ReadLine

Loop Until in_string ="!"

data_in=SerialPort1.ReadLine

Jeff T.

Bruce Bates

Folks -

What was said about the ECHO is correct, but that situation is limited to the use of Pin Port 16. This happens on ANY BS-2 model Stamp, not just the BS-2. If you use any other Pin Port, you will not experience the problem.

Regards,

Bruce Bates

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Programming can't be all that difficult, it's nothing but 1's and 0's

Unsoundcode

Thanks Bruce, I did think of that afterwards, it's certainly worth a mention.

Jeff T

Lapue

nv89 ? in Nuts and volts

realolman

thanks

you guys are really something

I know the format of what the BS 2 is going to send , so I guess I'll just use the last digits of it and ignore the rest

thank you