' 9-Bit Rs-485 Recieve test

Option default none
Option explicit

Dim rxdat As string ' Rx data assembly buffer
Dim a As string length 1 ' 9th bit - 1= adress - 0= data
Dim b As string length 1 ' 8 bits of Rx data
Dim address_match As float ' flag for data gate actions
'address_match=0 ' data gate is closed
Dim node As string length 1
node=Chr$(0) ' node address = 0
Print "node ";Asc(node)

'Open "com1:640000,2048,got_rx,20,de,9bit" As #1
Open "com1:640000,2048,9bit" As #1

Do
got_rx
Loop

Sub got_rx
If Loc(#1)>2 Then
a=Input$(1,#1)
b=Input$(1,#1)
If address_match Then ' if data gate open
If a="0" Then ' if is data byte
Print Asc(b);
rxdat=rxdat+b ' add data byte to assembly buffer
Else
If Len(rxdat) Then
Print " Buffer ";
Print Len(rxdat)
Print rxdat
rxdat=""
EndIf
address_match=0 ' close data gate
EndIf
Else
' Node address
' If A="1" And b=node Then address_match=1 ' open data gate
' any address
If A="1" Then address_match=1 ' open data gate
Print "Node ";Asc(b)
EndIf
EndIf
End Sub

End

MMBasic does not check that data is printed or read to/from the COM port in pairs. If your program
inadvertently sends or reads a single character it will disrupt all subsequent communications.
Note also that in 9 bit mode the size of the transmit and receive buffers are effectively halved because each
9 bit data item is stored as two bytes.

' 9-Bit Rs-485 Transmit test

Option default none
Option explicit

Dim a As string length 1 ' 9th bit - 1= adress - 0= data
Dim b As string length 1 ' 8 bits of Rx data

Open "com1:640800,2048,9bit" As #1

tx_node1
tx_node2

End

Sub tx_node1
Print #1,"1"+Chr$(0) ' node 0
Print #1,"0"+Chr$(65) ' A
Print #1,"0"+Chr$(66) ' B
Print #1,"0"+Chr$(67) ' C
End Sub

Sub tx_node2
Print #1,"1"+Chr$(1) ' node 1
Print #1,"0"+Chr$(68) ' D
Print #1,"0"+Chr$(69) ' E
Print #1,"0"+Chr$(70) ' F
End Sub

End

' 9-Bit Rs-485 Recieve test

Option default none
Option explicit

Dim a As string length 1 ' 9th bit - 1= adress - 0= data
Dim b As string length 1 ' 8 bits of Rx data

Open "com1:640800,2048,9bit" As #1

Do
got_rx
Loop

Sub got_rx
If Loc(#1)>2 Then
a=Input$(1,#1)
b=Input$(1,#1)
Print Asc(a);Asc(b)
End Sub

End