receiving 2 16bit numbers
| Author |
Message |
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<spen..
#1 / 4
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 receiving 2 16bit numbers Hi, I have managed to achieve this but it falls over sometimes when I assign the incomming four bytes to the two VB double variables. The error message is "overflow". Being new to this type of programming (RS232 data capture) I have cobbled it
up in "my own" way. What is the official way - it seems so hard to find
specific stuff in the VB 6 manual.
My hardware sends a.lowbyte, a.highbyte, c.lowbyte, c.highbyte and VB is set
to an interrupt when 4 bytes are received. The hardware can send any byte
value for all four bytes. Basically, I want to receive the two16 bit numbers
from the PIC microcontroller into two real numbers in VB - a and c.
After a lot of messing about I came up with what cannot be the right
solution (?) but it works except for the frequent overflows. The overflows
occur on the lines starting a=a+256 and c=c+256.
Case comEvReceive 'Received RThreshold # of chars Rthreshold =4
'receive 2 - 16-bit words
UStimes = MSComm1.Input
If UStimes <> "" Then
a = Asc(Mid(UStimes, 1, 1))
a = a + 256 * Asc(Mid(UStimes, 2, 2))
c = Asc(Mid(UStimes, 3, 3))
c = c + 256 * Asc(Mid(UStimes, 4, 4))
End If
DoEvents
draw_graph
UStimes = ""
'Case comEvSend ' There are SThreshold number of characters in the TX
buffer
End Select
It works but there must be a "proper" method to capture the four bytes into
two integers. In the above it has been necessary to capture them into
doubles.
any help would be appreciated
Spencer
|
| Mon, 03 Jun 2002 03:00:00 GMT |
|
 |
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Frank Lewi
#2 / 4
|
receiving 2 16bit numbers VB handles all intermediate variables as Ints unless told otherwise. Cast the intermediate as a Long, and your problem will go away. Also, your code appears to be specifying the incorrect "length"
parameter for the Mid function. It should look like this:
a = Asc(Mid(UStimes, 1, 1))
a = a + (256& * Asc(Mid(UStimes, 2, 1)))
c = Asc(Mid(UStimes, 3, 1))
c = c + (256& * Asc(Mid(UStimes, 4, 1)))
Enjoy!
Quote: >Hi, >I have managed to achieve this but it falls over sometimes when I assign the >incomming four bytes to the two VB double variables. The error message is >"overflow". >Being new to this type of programming (RS232 data capture) I have cobbled
it
>up in "my own" way. What is the official way - it seems so hard to find
>specific stuff in the VB 6 manual.
>My hardware sends a.lowbyte, a.highbyte, c.lowbyte, c.highbyte and VB is
set
>to an interrupt when 4 bytes are received. The hardware can send any byte
>value for all four bytes. Basically, I want to receive the two16 bit
numbers
>from the PIC microcontroller into two real numbers in VB - a and c.
>After a lot of messing about I came up with what cannot be the right
>solution (?) but it works except for the frequent overflows. The overflows
>occur on the lines starting a=a+256 and c=c+256.
> Case comEvReceive 'Received RThreshold # of chars Rthreshold =4
> 'receive 2 - 16-bit words
> UStimes = MSComm1.Input
> If UStimes <> "" Then
> a = Asc(Mid(UStimes, 1, 1))
> a = a + 256 * Asc(Mid(UStimes, 2, 2))
> c = Asc(Mid(UStimes, 3, 3))
> c = c + 256 * Asc(Mid(UStimes, 4, 4))
> End If
> DoEvents
> draw_graph
> UStimes = ""
> 'Case comEvSend ' There are SThreshold number of characters in the TX
>buffer
>End Select
>It works but there must be a "proper" method to capture the four bytes into
>two integers. In the above it has been necessary to capture them into
>doubles.
>any help would be appreciated
>Spencer
|
| Mon, 03 Jun 2002 03:00:00 GMT |
|
|
|
<spen..
#3 / 4
|
receiving 2 16bit numbers Hi, I have managed to achieve this but it falls over sometimes when I assign the incomming four bytes to the two VB double variables. The error message is "overflow". Being new to this type of programming (RS232 data capture) I have cobbled it
up in "my own" way. What is the official way - it seems so hard to find
specific stuff in the VB 6 manual.
My hardware sends a.lowbyte, a.highbyte, c.lowbyte, c.highbyte and VB is set
to an interrupt when 4 bytes are received. The hardware can send any byte
value for all four bytes. Basically, I want to receive the two16 bit numbers
from the PIC microcontrolle
r into two real numbers in VB - a and c.
After a lot of messing about I came up with what cannot be the right solution
(?) but it works except for the frequent overflows. The overflows occur on
the lines starting a=a+256 and c=c+256.
Case comEvReceive 'Received RThreshold # of chars Rthreshold =4
'receive 2 - 16-bit words
UStimes = MSComm1.Input
If UStimes <> "" Then
a = Asc(Mid(UStimes, 1, 1))
a = a + 256 * Asc(Mid(UStimes, 2, 2))
c = Asc(Mid(UStimes, 3, 3))
c = c + 256 * Asc(Mid(UStimes, 4, 4))
End If
DoEvents
draw_graph
UStimes = ""
'Case comEvSend ' There are SThreshold number of characters in the TX
buffer
End Select
It works but there must be a "proper" method to capture the four bytes into
two integers. In the above it has been necessary to capture them into
doubles.
any help would be appreciated
Spencer
|
| Mon, 03 Jun 2002 03:00:00 GMT |
|
|
|
Frank Lew
#4 / 4
|
receiving 2 16bit numbers VB handles all intermediate variables as Ints unless told otherwise. Cast the intermediate as a Long, and your problem will go away. Also, your code appears to be specifying the incorrect "length" parameter for
the Mid function. It should look like this:
a = Asc(Mid(UStimes, 1, 1))
a = a + (256& * Asc(Mid(UStimes, 2, 1)))
c = Asc(Mid(UStimes, 3, 1))
c = c + (256& * Asc(Mid(UStimes, 4, 1)))
Enjoy!
Quote: >Hi, >I have managed to achieve this but it falls over sometimes when I assign the >incomming four bytes to the two VB double variables. The error message is >"overflow". >Being new to this type of programming (RS232 data capture) I have cobbled
it
>up in "my own" way. What is the official way - it seems so hard to find
>specific stuff in the VB 6 manual.
>My hardware sends a.lowbyte, a.highbyte, c.lowbyte, c.highbyte and VB is
set
>to an interrupt when 4 bytes are received. The hardware can send any byte
>value for all four bytes. Basically, I want to receive the two16 bit
numbers
>from the PIC microcontroller into two real numbers in VB - a and c.
>After a lot of messing about I came up with what cannot be the right
>solution (?) but it works except for the frequent overflows. The overflows
>occur on the lines starting a=a+256 and c=c+256.
> Case comEvReceive 'Received RThreshold # of chars Rthreshold =4
> 'receive 2 - 16-bit words
> UStimes = MSComm1.Input
> If UStimes <> "" Then
> a = Asc(Mid(UStimes, 1, 1))
> a = a + 256 * Asc(Mid(UStimes, 2, 2))
> c = Asc(Mid(UStimes, 3, 3))
> c = c + 256 * Asc(Mid(UStimes, 4, 4))
> End If
> DoEvents
> draw_graph
> UStimes = ""
> 'Case comEvSend ' There are SThreshold number of characters in the TX
>buffer
>End Select
>It works but there must be a "proper" method to capture the four bytes into
>two integers. In the above it has been necessary to capture them into
>doubles.
>any help would be appreciated
>Spencer
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| Mon, 03 Jun 2002 03:00:00 GMT |
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