XDIMAX Products Forum

Hi,

I am using the SUB -20 to write outputs of several PCF8574 that controls relays. I can write to a single outputs, But I am not able to write another output without changing the other output .
What I a want to do is write the different outputs separately. Can anyone help. I am using VB.net 2010.
Thanks.

Hi,
Drop us a piece of your code and we will tell you where the problem is.

Code to write to several PCF8574 only writing one output

'START WRITE PINS
Private Sub DoI2CWrite_pin(ByVal Card As String, ByVal data As String, ByVal test As Boolean)
'local variable

Dim Sub20 As New Xdimax.Sub20
Dim StrBytes As String()
Dim Bytes As Byte()
Dim i As Integer
Dim N As Integer
Dim WriteData1 As String = ""
Dim pinnumber As String = ""
Dim StringData As String = ""
Dim address As String = ""
'Read address for card
If Card = 1 Then
address = "38"
pinnumber = "01"
ElseIf Card = 2 Then
address = "39"
pinnumber = "02"
ElseIf Card = 3 Then
address = "3a"
pinnumber = "03"
ElseIf Card = 4 Then
address = "3b"
pinnumber = "04"
ElseIf Card = 5 Then
address = "3c"
pinnumber = "05"
ElseIf Card = 6 Then
address = "3d"
pinnumber = "06"
ElseIf Card = 7 Then
address = "3e"
pinnumber = "07"
ElseIf Card = 8 Then
address = "3f"
pinnumber = "08"
ElseIf Card = 9 Then
address = "20"
pinnumber = "09"
ElseIf Card = 10 Then
address = "21"
pinnumber = "10"
ElseIf Card = 11 Then
address = "22"
ElseIf Card = 12 Then
address = "23"
ElseIf Card = 13 Then
address = "24"
'text from label
End If
If data = "1" Then
WriteData1 = "00"
StringData = Label_NC.Text
ElseIf data = "2" Then
WriteData1 = "01"
StringData = Label_Ground.Text
ElseIf data = "3" Then
WriteData1 = "02"
StringData = Label_Heater.Text
ElseIf data = "4" Then
WriteData1 = "04"
StringData = Label_Screen1.Text
ElseIf data = "5" Then
WriteData1 = "08"
StringData = Label_Screen2.Text
ElseIf data = "6" Then
WriteData1 = "20"
StringData = Label_Anode.Text
ElseIf data = "7" Then
WriteData1 = "10"
StringData = Label_Screen3.Text
ElseIf data = "8" Then
WriteData1 = "40"
StringData = Label_Test_1.Text
ElseIf data = "9" Then
WriteData1 = "80"
StringData = Label_Test_2.Text
End If

Sub20 = New Xdimax.Sub20

If 0 = DeviceList.Items.Count Then
AddInfoLine("ERROR: No device")
Return
End If
If Not Sub20.Open(DeviceList.SelectedItem.Ref) Then
AddInfoLine("ERROR: Cannot open SUB-20 WrtPIN")
Return
End If
'---------------------------------------------------------------------------------

StrBytes = Split(WriteData1, " ")
If StrBytes(0).Length = 0 Then
N = 0
Else
N = StrBytes.Length
End If

Bytes = Array.CreateInstance(GetType(Byte), N)

For i = 0 To N - 1
Bytes(i) = Val("&H" + StrBytes(i))
Next

If Not Sub20.I2C_Write(Val("&H" + address), _
Val("&H" + "1"), Val("&H" + "0"), Bytes) Then
AddInfoLine("failed, err=" + Sub20.GetLastError().ToString())
End If
If test = 0 Then
AddInfoLine("Connect pin: " + pinnumber + " to " + StringData)
End If

Sub20.Close()

End Sub

OK,
Now tell us in plain English with register addresses and values, what are you doing, what do you expect to get and what actually happens.

Hi,

The address range for the PCF8574 is &H20 to &H27 and for PCF8574A is &H38 to &H3F.
To write a output data is &H01'(bin 1) for ouput 1, &H02(bin 10) for ouput 2, &H04 (bin 100)for ouput3, &H08 (bin1000) for output 4 etc.

My problem is when output1 is 1 and I want to write output 3 on the same PCF8574(A) a don't know how to do this. If you write output 3, output 1 goes low.
If you want 1 and 3 high then the data is &H01 + &H03 = &H04 (bin101).
I expect to write each single output (1 to 8) seperately, without disturbing the other outputs.
Something like write_output (address, number of output, on or off).
Hope this helps.
Regards

OK,
But how is it related to SUB-20? You should talk to PCF8574 manufacturer.
SUB-20 is only a channel between your PC program and PCF.