recently to do a project, the use ofS7-200, but not a great amount of data exchange, andWINCCfeel compared to waste, so wanted to be their own monitoring software, on the thought of usingVBprogramming to callw95_s7.dlldynamic-link database. through3-day efforts, and finally the results of small, what is my basic method of test. For your reference!
1.Prodave forpc withs7 series ofplc data link communications between the toolbox. The essence is that the user by calling the "w95_s7.dll"such as library function to solve the PLC withPCbetween the data exchange and data-processing problem. by hardware required for:CPU22x, PC / PPIprogramming cable, withCOMpopulationPC. This is probably the simplest configuration, it is easy to achieve the purpose of the pilot. Here do not need to installProdavesoftware, as long as the"w95_s7.dll"paper copy to your program to the directory can be.2. communication settings: Open "Control Panel" in "SettingsPG / PCinterface" option in the "access point applications "list box, select"S7ONLINE (STEP7) PC / PPI Cable",in its attributes of "overtime" to set up big points, here set to100ms, "baud rate" is set to9.6kbps (because mypc / ppicables made in China, does not support multi-master), "address" for the0.3. Source Code: PLCprocedures:LD I0.0 MOVW 4766, VW0 VBprocedures:
****a statement in the module****:
Public plcadr As plcadrtype
Public gb_PlcConnected As Boolean
Type plcadrtype
adr As Byte 'station address, the default value for2
SEGMENTID As Byte 'paragraph identifier, fixed value of0
SLOTNO As Byte 'slot number, the default value of2
RACKNO As Byte 'rack number,0
End Type
Public Res As Long
Declare Function load_tool Lib "w95_s7.dll" (ByVal nr As Byte, ByVal dev As String, adr As plcadrtype) As Long
....... fixed 'omitted other defined functions.
Declare Function as200_vs_field_read Lib "w95_s7.dll" (ByVal nr As Long, ByVal anz As Long, value As Byte) As Long 'Reading200PLC Vstore data function
****a statement in the form****
Private Sub Form_Load ()
Dim buffer ( 1) As Byte
plcadr.adr = 2
plcadr.SEGMENTID = 0
plcadr.SLOTNO = 2
plcadr.RACKNO = 0
Res = load_tool (1, "S7ONLINE", plcadr)
Res = as200_vs_field_read (0, 2, buffer (0))
If Res <> 0 Then
MsgBox (" PLCconnection error")
gb_PlcConnected = False
Else
gb_PlcConnected = True
MsgBox ( "plcconnected correctly")
Label1.Caption = buffer (0) * 256 buffer (1)
End If
End Sub
through the above-mentioned procedure can be correctly read out thePLCdata. can be extended after the content, the preparation of a monitoring software.
