MsComm control Pass byte data to output

My question comes from the MsComm control.

I am trying to write a test program to control a microcontoler that I have programed.  The Microcontroler has  12 commands that it receivers from and rs232 interface programed into the chip.  What I am trying to do is to build an operations interface for the microcontroler.  What I am trying to do.

When I click on a button I want to send out a byte string.
Say command 1, I want to send eight bits that are "00000001".  I am trying to use this code

Private Sub Command1_Click()
Dim Buffer As Variant
Dim Channel1 As Byte
Channel1 = 1
Buffer = Channel1
MSComm1.CommPort = 3
MSComm1.PortOpen = True

MSComm1.Output = Channel1

Now the VB Books on line tells me that the type BYTE is

"Byte variables are stored as single, unsigned, 8-bit (1-byte) numbers ranging in value from 0–255"

Well this is what I want to output
But when I use my code I get an error saying type mismatch.

The Vb books online say this

To send binary data, you must pass a Variant which contains a byte array to the Output property.


What am I doing wrong.

jaalexAsked:
Who is Participating?

[Product update] Infrastructure Analysis Tool is now available with Business Accounts.Learn More

x
I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

alamoCommented:
I don't know why the documentation claims you need to use a byte array for binary data, except that a binary array is slightly easier to work with than a string. Passing it through a variant probably should convert it to a string for the MSComm control, but I experience the same results as your do.

The MSComm control needs a string, so give it a string - who cares if the data is binary:

Dim strBuffer As String
strBuffer = Chr$(1)
MSComm1.CommPort = 3
MSComm1.PortOpen = True
MSComm1.Output = strBuffer

For binary data don't forget to set Handshaking to None or RTS/CTS, and NullDiscard to False. Good luck!
0
jaalexAuthor Commented:
Ok so I can pass a string.    But using the chr$ function will I get the byte information.

The micro will only understand  

Start bit + eight data bits + stop

The commands can only be

Start + "00000000" + stop
Start + "00000001" + stop

Anyway you get the picture.  

I read in the doc that if I do

Dim buffer as String

buffer = Chr(67)  

I will return an A value.   Is this the same as a Chr$

If you feel you need more points I will add them
0
alamoCommented:
Yes, Chr and Chr$ are basically the same, VB is trying to get away from $ to denote strings but I use it out of habit. Actually, I just looked the the help and they have changed Chr so it deals "properly" with double-byte character sets; ChrB is guaranteed to return just 1 character, used for the sort of thing you need.

So 'Start + "00000000" + stop' would be ChrB(0), 'Start + "00000001" + stop' would be ChrB(1).

(Actually, Chr(65) is "A", not Chr(67), which is "C").

Let me know how it works... the points are fine. By the way, you can leave a comment without rejecting the answer if you need more information or clarification; when you leave a comment I get an email notifying me so I can check.
0

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
jaalexAuthor Commented:
OK cool  I will check it out.

Thanks for the info
0
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today
Visual Basic Classic

From novice to tech pro — start learning today.