手邊有兩個USB to Uart 的傳輸線都不能使用，可能是PL2303又掛了，所以這次不使用2303的IC，想要改裝成CH340的試試
從官網上查到有一個CH340N type，封裝只有8 pin，又不用外加振盪器，就入手了幾顆進行測試
首先當然是把PL2303從板子上移開，振盪器也卸除掉，如下圖
接著找看看有沒有相關的Pin 腳可以直接焊接就好
MEASure:VOLTage:DC?;:MEASure:CURRent:AC?當然首先要先安裝電腦端的驅動程式，因為電表是使用Keysight的，所以就上Keysight網站找驅動程式了，下載網址
'--- General define ---
Private Declare Sub Sleep Lib "kernel32" (ByVal dwMilliseconds As Long) 'declare to use "sleep"
Dim ioMgr As VisaComLib.ResourceManager
Dim instrument As VisaComLib.FormattedIO488
'--- function define ---
Dim ioMgr As VisaComLib.ResourceManagerDim instrument As VisaComLib.FormattedIO488
Dim sndBuffer As String
Dim rcvBuffer As String
Set ioMgr = New VisaComLib.ResourceManager
Set instrument = New VisaComLib.FormattedIO488
Set instrument.IO = ioMgr.Open("USB0::10893::4865::MY59022278::0::INSTR")
instrument.SetBufferSize IO_IN_AND_OUT_BUFS, 64instrument.WriteString "*IDN?" Debug.Print instrument.ReadString讀取電壓與電流的程式如下
'--------------------------
' Volt
'--------------------------
status = commSend(instrument, "SENSe:VOLTage:DC:NULL:VALue:AUTO 1")
status = commSend(instrument, "CONFigure:VOLTage:DC 10,0.001") ' mV resolution
status = commSend(instrument, "SAMPle:COUNt 1")
status = commSend(instrument, "*WAI")
rcvBuffer = commQuery(instrument, "READ?")
'--------------------------
' Current
'--------------------------
status = commSend(instrument, "SENSe:CURRent:DC:NULL:VALue:AUTO 1")
status = commSend(instrument, "CONFigure:CURRent:DC 1E-6")
status = commSend(instrument, "CURRent:DC:RES 1E-6") ' uA resolution
status = commSend(instrument, "SAMPle:COUNt 1")
status = commSend(instrument, "*WAI")
rcvBuffer = commQuery(instrument, "READ?")
電表是使用USB連接，後來要控制R&S示波器，就想改用TCP/IP的方式試試，也是OK的喔，下面列出幾個範例，讀取波形電壓平均值、上升時間及波形的各點電壓資料'==================================
' R&S RTM3004 波形平均值
'==================================
instrument.WriteString "TRIGger:A:EDGE:SLOpe NEGative"
instrument.WriteString "MEASurement1:SOURce CH2"
instrument.WriteString "MEASurement1:MAIN MEAN"
instrument.WriteString "MEASurement1:RESult? MEAN"
'==================================
'Measure rise time
'==================================
instrument.WriteString "TRIGger:A:EDGE:SLOpe NEGative"
instrument.WriteString "MEASurement1:SOURce CH2"
instrument.WriteString "REFLevel:RELative:MODE TEN" ' 10% - 90%
instrument.WriteString "MEASurement1:MAIN RTIMe"
instrument.WriteString "MEASurement1:RESult?"
'==================================
' Wave RAW data
'==================================
instrument.WriteString "TRIGger:A:MODE NORMal" ' Normal trigger
instrument.WriteString "TRIGger:A:EDGE:SLOpe NEGative" ' Negative edge
instrument.WriteString "FORM ASC" ' output format ASCii
instrument.WriteString "FORM:BORD LSBF"
instrument.WriteString "CHAN1:DATA:POIN DEF"
instrument.WriteString "SINGle" ' Single trigger
instrument.WriteString "CHANnel1:DATA:HEAD?"
Debug.Print instrument.ReadString
instrument.WriteString "CHANnel1:DATA?"
Debug.Print instrument.ReadString
下面是UART、USB與TCP/IP的宣告方式'=========
'UART
'=========
Set instrument.IO = ioMgr.Open("ASRL6::INSTR") ' COM6
Dim serInfc As VisaComLib.ISerial
Set serInfc = instrument.IO
serInfc.BaudRate = 9600 ' 9600bps baud rate
serInfc.FlowControl = ASRL_FLOW_NONE
serInfc.Timeout = 10000
instrument.IO.SendEndEnabled = True
instrument.IO.TerminationCharacter = 10 ' could be 10 (line feed) or 13 (carriage return)
instrument.IO.TerminationCharacterEnabled = True
instrument.IO.Timeout = 10000
'=========
'USB
'=========
Set instrument.IO = ioMgr.Open("USB0::0x0AAD::0x01D6::104068::INSTR")
instrument.SetBufferSize IO_IN_AND_OUT_BUFS, 64
Set serInfc = instrument.IO
'=========
'TCP/IP
'=========
Set instrument.IO = ioMgr.Open("tcpip0::192.168.0.13::instr") ' ip addr 192.168.0.13
instrument.SetBufferSize IO_IN_AND_OUT_BUFS, 64
Set serInfc = instrument.IO
下面是用Arduino與ADS1015做的4通道電表，解析度至小數第二位，使用VBA透過UART讀取電表至Excel表格中
