最近在开发项目进行测试时,每次都要架设实体机器,很不方便,于是就想着可不可以写一个虚拟的机器,便于测试。我们项目与机器的通信方式是基于COM口的,于是要做虚拟机器,首先要解决的问题是创建虚拟的COM口。
网上搜索一番,主要有VSPM和VSPD,前者是在WIN7前使用稳定,后者在WIN7中使用稳定。我的电脑是WIN7_64的,所以选用了VSPD7。于是下了个VSPD7.1的安装包,安装完成后,利用软件界面就可以创建相应的虚拟COM口了。具体如何使用,可以参看这篇文章《虚拟串口VSPD的使用方法》。记住一点,VSPD的COM通信是成对的,一个用于接收数据,一个用于发送数据。
有了虚拟COM口后,就是写一个DEMO进行测试。具体可以参看这篇文件章《win7系统下用vspd软件进行串口编程实例》。
当虚拟COM口可以实现通讯之后,就想着我们的程序是依赖于这个VSPD安装包的,那如果我们是否可以不依赖呢?有两种方案:
方案一:自己写一个虚拟COM的驱动,然后里面实现。有兴趣的可以参看该文《开发虚拟串口驱动程序》。
方案二:VSPD安装包是一个安装程序,为了实现虚拟COM,必然会有相应的驱动。如果我们能够找到这个驱动并安装,之后用相应的接口来调用,或是可行。
方案一想了,但自认还没有这个能耐,于是果断放弃,退而选方案二。那么方案二要实现,首先要解决的问题是接口的调用,因为驱动程序即使不能做到自己安装,但还是可以通过VSPD安装包的安装来解决,那么VSPD中有没有提供这样的接口呢?
查看VSPD的用户手册(User Manual),里面果然有相应的接口(在Using serial port driver in your program下的Functions中),于是有C#写了相应的调用,下面是代码。
using System; using System.Collections.Generic; using System.Linq; using System.Text; //Add using System.Runtime.InteropServices; namespace Anser.U2Simulator.Model { public class VSPD { //[DllImport("VSPDCTL.dll", EntryPoint = "CreatePair", CallingConvention = CallingConvention.StdCall, CharSet = CharSet.Auto)] //public static extern bool CreatePair(byte[] comName1, byte[] comName2); /// <summary> /// CreatePair creates a pair of virtual serial ports with given names. /// It accepts two null-terminated strings determining which ports should be created as input. /// For example, "COM5" and "COM6". /// </summary> /// <param name="comName1">A null-terminated string that defines the name of the first port in a pair</param> /// <param name="comName2">A null-terminated string that defines the name of the second port in a pair</param> /// <returns>CreatePair returns TRUE if virtual serial pair was created successfully and FALSE otherwise</returns> [DllImport("vspdctl.dll")] public static extern bool CreatePair(string comName1, string comName2); /// <summary> /// DeletePair deletes a pair of virtual serial ports with a given name. /// As input it takes name of any virtual serial port in a pair. /// For example, if you want to remove pair named "COM5"-"COM6", /// you can pass either "COM5" or "COM6" as argument to DeletePair function. /// </summary> /// <param name="comName"> A null-terminated string that defines one of the two port names in a pair you want to delete </param> /// <returns>DeletePair returns TRUE if virtual serial pair was successfully deleted and FALSE otherwise</returns> [DllImport("vspdctl.dll")] public static extern bool DeletePair(string comName); /// <summary> /// DeleteAll deletes all virtual serial ports currently present in a system. It accepts no arguments at input. /// </summary> /// <returns>DeleteAll returns TRUE if all virtual serial pairs were successfully deleted and FALSE otherwise</returns> [DllImport("vspdctl.dll")] public static extern bool DeleteAll(); [DllImport("vspdctl.dll")] public static extern bool SetStrictBaudrateName(string comName, bool isStrictBaudrate); [DllImport("vspdctl.dll")] public static extern bool SetStrictBaudrateHandle(IntPtr handle, bool isStrictBaudrate); /// <summary> /// SetStrictBaudrate enables/disables full baudrate emulation, /// needs the name of one of the paired virtual ports and boolean parameter /// that defines if strict baudrate emulation should be enabled or not. /// </summary> /// <param name="comName">A null-terminated string that defines one of the two port names in a pair </param> /// <param name="isStrictBaudrate">A boolean variable which should be TRUE /// if you want to enable strict baudrate emulation and FALSE if you want to disable it</param> /// <returns>SetStrictBaudrate returns TRUE if strict baudrate emulation was successfully enabled and FALSE otherwise</returns> [DllImport("vspdctl.dll")] public static extern bool SetStrictBaudrate(string comName, bool isStrictBaudrate); /// <summary> /// SetBreak enables/disables line break emulation in virtual serial ports. /// </summary> /// <param name="comName">A null-terminated string that defines one of the two port names in a pair</param> /// <param name="isBreak"> A boolean variable should be TRUE if you want to emulate connection break and FALSE if you want to re-establish it </param> /// <returns>SetBreak returns TRUE if line break emulation was successfully enabled and FALSE otherwise.</returns> [DllImport("vspdctl.dll")] public static extern bool SetBreak(string comName, bool isBreak); /// <summary> /// QueryBus: QueryBus sends request to get complete information from the virtual serial bus installed by VSPD. /// </summary> /// <param name="inBufferPtr">A pointer to VSBUS_QUERY or VSBUS_QUERY_EX structures. /// If you want to get information about all current virtual serial ports /// then use VSBUS_QUERY structure /// and if you want to get extended information /// about single virtual serial pair then use VSBUS_QUERY_EX structure.</param> /// <param name="inBufferSize"></param> /// <param name="outBufferPtr"></param> /// <param name="outBufferSize">A pointer to either PORT_INFORMATION or PORT_INFORMATION_EX structures list. /// If you have used VSBUS_QUERY than you should get PORT_INFORMATION list /// and if you used VSBUS_QUERY_EX then you should get PORT_INFORMATION_EX.</param> /// <returns></returns> [DllImport("vspdctl.dll")] public static extern bool QueryBus(IntPtr inBufferPtr, long inBufferSize, IntPtr outBufferPtr, long outBufferSize); /// <summary> /// SetWiring sets custom signal lines wiring (pinout). /// </summary> /// <param name="comName">A null-terminated string that defines one of the two port names in a pair </param> /// <param name="bufferPtr">A pointer to VSERIAL_WIRING structure </param> /// <param name="bufferSize">Size of Buffer parameter in bytes </param> /// <returns>SetWiring returns TRUE if signal lines wiring was created successfully and FALSE otherwise</returns> [DllImport("vspdctl.dll")] public static extern bool SetWiring(string comName, IntPtr bufferPtr, long bufferSize); /// <summary> /// SetAccessList restricts access to created virtual serial ports for various applications. /// </summary> /// <param name="comName"> A null-terminated string that defines one of the two port names in a pair </param> /// <param name="bufferPtr">A pointer to PROGRAM_ACCESS array </param> /// <param name="bufferSize">Size of Buffer parameter in bytes </param> /// <returns>SetAccessList returns TRUE if port access list was created successfully and FALSE otherwise</returns> [DllImport("vspdctl.dll")] public static extern bool SetAccessList(string comName, IntPtr bufferPtr, long bufferSize); //[StructLayout(LayoutKind.Sequential,CharSet=CharSet.Ansi,Pack=1)] public struct _VSBUS_QUERY { /// <summary> /// VSBUS_QUERY structure size /// </summary> ulong Size; /// <summary> /// Has QUERYTYPE_PORTS = 1 value. Can be extended in the future. /// </summary> ulong QueryType; }; private const int MAX_PORTNAME_LEN = 6; public struct _VSBUS_QUERY_EX { /// <summary> /// VSBUS_QUERY_EX structure size /// </summary> ulong Size; /// <summary> /// 1:query all virtual ports. /// 2:query particular virtual pair /// 3:query particular virtual pair; name of the application, which created the port, is returned. /// </summary> ulong QueryType; /// <summary> /// Unicode name of any port in the pair you want to delete. /// For instance, if "COM6-COM7" virtual serial ports pair was created, /// then to remove it, PortName's value should be COM6 or COM7. /// </summary> [MarshalAs(UnmanagedType.ByValTStr, SizeConst = MAX_PORTNAME_LEN)] string PortName; } } }代码中用到的结构只写了一部分,如果需要用到更多的结构的,可以参看VSPD的使用手册,然后自行改造。
在这些接口中我要用的只是创建和册除虚拟COM口,所以只要用到CreatePair、DeletePair和DeleteAll,下面是对这三个接口调用的示例代码。
VSPD.CreatePair("COM101", "COM201"); VSPD.DeletePair("COM101"); VSPD.DeleteAll();使用COM101和COM201,是为了更方便从名字上看出他们是一对的。
有了这些之后,那么自己增删虚拟COM口已经可以实现了。那么还剩下另一个问题,就是能不能从VSPD的安装包中解出相应的驱动程序。
经过一番试验后,找到了一种方法,具体步骤如下
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