Requirements: Use Labwindows_cvi software to develop the whole machine calibration system.

Analysis: The whole machine calibration system is an integrated control system. The hardware that needs to be programmed mainly includes: vector network analyzer, scanning frame, turntable, timing controller, etc. A set of calibration process is formed through the control of these hardware. At present, These hardwares are controlled separately, because the scanning frame, turntable, and timing controller are non-standard instruments, so they will not be described in detail here. So this chapter mainly describes the Labwindows_cvi program-controlled vector network analyzer based on c language.

This chapter mainly consists of several parts: connecting the instrument, sending instrument commands, and receiving instrument data.

Table of contents

1 Use of the VISA function library in Labwindows_cvi

1.1 Resource Management

1.2 Resource template

1.3 Specific Resource Operations

1.4 VISA common functions

2 Labwindows_cvi programming based on c language

2.1 Interface design

2.2 Implementation code

2.3 Function display

1 Use of the VISA function library in Labwindows_cvi

The VISA function library provided in Labwindows_cvi is an implementation of the standard VISA. Open the function panel selection window of the VISA function library, and you can see that it contains 3 subclasses.

● resource management;

● resource template;

• Operations on specific resources.

The resource management subclass implements the resource location and interface communication life cycle control in the VISA standard; the resource template subclass implements the attribute control, resource locking service and event mechanism in the VISA standard; the specific resource operation subclass implements the VISA standard Medium I/O control.

1.1 Resource Management

Resource management includes resource location and life cycle control of communication. Resource location is a function viOpenDefaultRM, which realizes the location of all VISA resources on the machine, and returns the resource handle of ViSession type through the pointer. Communication lifecycle control for all specific resources is implemented through this handle. Communication lifecycle control includes opening resources, finding resources, and closing resources.

1.2 Resource template

Resource template subclass provides VISA attribute control, resource locking service and event mechanism. This part of the content is not reflected in this article, so it will not be described in detail.

1.3 Specific Resource Operations

Resource-specific operations include message-based communication functions and register-based communication functions.

1.3.1 Message-based communication functions

Message-based instruments have separate processors that interpret received information and interpret the information into instructions or data. VISA provides formatted I/O and basic I/O functions for message-based communication.

(1) Format I/O function

Very similar to the standard C formatting functions, it can send or receive formatted data, including: viPrintf(), viScanf(), viQueryf(), viFlush().

(2) Basic I/O functions

Basic I/O supports synchronous and asynchronous data transmission in two ways.

The function of synchronous transmission terminates the execution of other programs during the calling process, and does not return until the data is received or sent. The functions that support synchronous transmission include viWrite, viRead, viClear, viAssertTrigger and viReadSTB.

The asynchronous transfer function returns immediately after being called, and an asynchronous read and write completion event (VI_EVENT_IO_COMPLETION) is generated after the data transfer is completed, and the VI_EVENT_IO_COMPLETION event can be processed through event queuing or callback function.

1.3.2 Register-based communication functions

Do not elaborate here.

1.4 VISA common functions

1.4.1 Positioning of VISA resource manager - viOpenDefaultRM

原型：ViStatus viOpenDefaultRM ( ViSession sesn);

Description: This function is used to initialize a VISA resource manager, this function must be called before any other VISA functions.

Table 1-1 viOpenDefaultRM function parameters

parameter	describe
sound	Returns an individual VISA resource manager ID

Table 1-2 return value of viOpenDefaultRM function

identifier	value	describe
VI_SUCCESS	0	VISA Explorer initialized successfully.
VI_ERROR_ALLOC		Insufficient system resources.
VI_ERROR_INV_SETUP		The configuration file is invalid or does not exist.
VI_ERROR_SYSTEM_ERROR		VISA system initialization failed.

1.4.2 Connecting Instruments——viOpen

原型：ViStatus viOpen ( ViSession sesn, ViRsrc name, ViAccessMode mode, ViUInt32 timeout, ViSession vi);

Description: Connect to a specified device and return a connection identifier that can be used to call other functions.

Table 1-3 viOpen function parameters

parameter	direction	describe
sound	IN	VISA Explorer Logical Identifier
name	IN	address name
mode	IN	Connection opening method, which can be the following values: VI_EXCLUSIVE_LOCK is opened exclusively; VI_LOAD_CONFIG opens according to the external configuration file VI_NULL normal multi-access open
timeout	IN	If it is opened exclusively, the parameter is an absolute time (in ms), and an error will be returned when the timeout expires. Other connection methods ignore this value.
vi	OUT	Returns the open connection logical identifier

Table 1-4 return value of viOpen function

identifier	value	describe
VI_SUCCESS	0	connection succeeded.
VI_SUCCESS_DEV_NPRESENT		The connection was successful, but there is no response from the specified address.
VI_WARN_CONFIG_NLOADED		The specified address does not exist or the address format is incorrect.
VI_ERROR_ALLOC		Insufficient system resources.
VI_ERROR_INTF_NUM_NCONFIG		The specified address is valid, but cannot be used.
VI_ERROR_INV_ACC_MODE		Illegal access mode.
VI_ERROR__INV_RSRC_NAME		Address name syntax error.
VI_ERROR__INV_SESSION VI_ERROR__INV_OBJECT		invalid vi.
VI_ERROR_LIBRARY_NFOUND		The VISA library is not fully loaded.
VI_ERROR_NSUP_OPER		Explorer seen does not support this function.
VI_ERROR_RSRC_BUSY		seen is valid, but currently inaccessible.
VI_ERROR_RSRC_LOCKED		seen is monopolized.
VI_ERROR_RSRC_NFOUND		Insufficient information or resource does not exist.
VI_ERROR_TMO	0Xbfff0015	The operation timed out.

1.4.3 Sending Instrument Commands - viPrintf and viWrite

（1）viPrintf

原型：ViStatus viPrintf ( ViSession vi, ViString writeFmt, ...);

Description: Format a string and send the formatted string to the device. (String formatting can refer to the Format function in the CString class in MFC.)

The viWrite and viPrintf functions cannot be used simultaneously on the same resource.

The parameters of some VISA functions are variable (such as viPrintf, viScanf and viQueryf), which causes VB to fail to call. Users can use functions equivalent to these functions instead.

The writeFmt parameter can contain ordinary characters, general formatting characters, and special characters. Ordinary characters (including spaces) are written as usual without any modification. A backslash (\) should be added in front of the special character; the format character is composed of a percent sign (%) and an operation flag, which will be introduced later.

Table 1-5 Special characters

\n	Sends an ASCII newline character, and the END flag is automatically sent along with it.
\r	Send an ASCII carriage return.
\t	Send an ASCII tab character.
\###	Send a specified octal number.
\”	Send an ASCII double quote.
\\	Send an ASCII backslash.

Table 1-6 viPrintf function parameters

parameter	direction	describe
vi	IN	object identifier
writeFmt	IN	format string

表1-7 viPrintf函数返回值

标识符	值	描述
VI_SUCCESS	0	参数成功格式化。
VI_ERROR_ALLOC		内存不足。
VI_ERROR_INV_FMT		writeFmt包含无效格式化说明符。
VI_ERROR__INV_SESSION VI_ERROR__INV_OBJECT		vi不能标志正确的连接。
VI_ERROR_IO		位置IO错误。
VI_ERROR_NSUP_FMT		writeFmt有不支持的格式说明符。
VI_ERROR_RSRC_LOCKED		vi被独占。
VI_ERROR_TMO		操作超时。

（2）viWrite

原型：ViStatus viWrite (ViSession vi, ViBuf buf, ViUInt32 cnt, ViPUInt32 retCnt);

描述：同步写入数据。写入的数据存储在buf中。当数据写入完毕函数才返回。任何时间都只能存在一个同步写入。

如果retCnt的值为VI_NULL，将不返回写入数据长度值。

表1-8 viWrite函数参数

参数	方向	描述
vi	IN	对象标识符
buf	IN	写入数据存放地址。
cnt	IN	指定写入长度。
retCnt	OUT	实际写入长度，如果为VI_NULL表示不关心该值。

表1-9 viWrite函数返回值

标识符	值	描述
VI_SUCCESS	0	成功读取，读取到END指示器结束。
VI_SUCCESS_MAX_CNT		成功读取，已经达到最大长度cnt。
VI_SUCCESS_TERM_CHAR		成功读取，读取到特定终止符。
VI_ERROR_ASRL_FRAMING		格式错误。
VI_ERROR_ASRL_OVERRUN		溢出错误。
VI_ERROR_ASRL_PARITY		同步错误。
VI_ERROR_BERR		总线错误。
VI_ERROR_CONN_LOST		连接丢失。
VI_ERROR_INV_SESSION VI_ERROR_INV_OBJECT		vi不能标志正确的连接。
VI_ERROR_INV_SETUP		设置无效，不能执行操作。
VI_ERROR_IO		位置I/O是错误。
VI_ERROR_NCIC		非法控制器。
VI_ERROR_NLISTENERS		没有检测到听者。
VI_ERROR_NSUP_OPER		vi不支持此函数。
VI_ERROR_OUTP_PROT_VIOL		设备报告输出协议错误。
VI_ERROR_RAW_RD_PROT_VIOL		传输时读协议被破坏。
VI_ERROR_RAW_WD_PROT_VIOL		传输时写协议被破坏。
VI_ERROR_RSRC_LOCKED		vi被独占。
VI_ERROR_TMO		操作超时。

1.4.4 接收仪器数据——viScanf或viRead

（1）viScanf

原型：ViStatus viScanf (ViSession vi, ViString readFmt,arg1,arg2, ...);

描述：这操作从设备读取一个字符串，然后格式化后保存值arg变量中。格式化字符串包含说明符、空格字符和普通字符。

VISA中参数不确定的函数（viPrintf,viScanf,和viQueryf）不能被 VB调用。可以用功能相似的viVPrintf,viVScanf,和viVQueryf代替。

表1-10 viScanf函数参数

参数	方向	描述
vi	IN	对象标识符
readFmt	IN	格式化字符串。

表1-11 viScanf函数返回值

标识符	值	描述
VI_SUCCESS	0	成功读到数据并且格式化到arg参数里。
VI_ERROR_ALLOC		内存不足。
VI_ERROR_INV_FMT		readFmt包含无效格式化说明符。
VI_ERROR__INV_SESSION VI_ERROR__INV_OBJECT		vi不能标志正确的连接。
VI_ERROR_IO		位置IO错误。
VI_ERROR_NSUP_FMT		readFmt有不支持的格式说明符。
VI_ERROR_RSRC_LOCKED		vi被独占。
VI_ERROR_TMO		操作超时。

（2）viRead

原型：ViStatus viRead (ViSession vi, ViPBuf buf, ViUInt32 cnt, ViPUInt32 retCnt);

描述：同步读取数据。读取的数据存在buf中，当数据读取完毕函数才返回。任何时间都只能存在一个同步读取。遇到以下情况同步读取结束：

1）收到END指示器；

2）读取到终止符；

3）读取的数据大小达到cnt的值。

注意：必须设置读取终止符。

表1-12 viRead函数参数

参数	方向	描述
vi	IN	对象标识符
buf	OUT	返回数据存取地址。
cnt	IN	指定读取长度。
retCnt	OUT	实际读取长度，如果为VI_NULL表示不关心该值。

表1-13 viRead函数返回值

标识符	值	描述
VI_SUCCESS	0	成功读取，读取到END指示器结束。
VI_SUCCESS_MAX_CNT		成功读取，已经达到最大长度cnt。
VI_SUCCESS_TERM_CHAR		成功读取，读取到特定终止符。
VI_ERROR_ASRL_FRAMING		构架错误。
VI_ERROR_ASRL_OVERRUN		溢出错误。
VI_ERROR_ASRL_PARITY		同步错误。
VI_ERROR_BERR		总线错误。
VI_ERROR_CONN_LOST		连接丢失。
VI_ERROR_INV_SESSION VI_ERROR_INV_OBJECT		vi不能标志正确的连接。
VI_ERROR_INV_SETUP		设置无效，不能执行操作。
VI_ERROR_IO		位置I/O是错误。
VI_ERROR_NCIC		非法控制器。
VI_ERROR_NLISTENERS		没有检测到听者。
VI_ERROR_NSUP_OPER		vi不支持此函数。
VI_ERROR_OUTP_PROT_VIOL		设备记录一个输出协议错误。
VI_ERROR_RAW_RD_PROT_VIOL		传输时读协议被破坏。
VI_ERROR_RAW_WD_PROT_VIOL		传输时写协议被破坏。
VI_ERROR_RSRC_LOCKED		vi被独占。
VI_ERROR_TMO		操作超时。

1.4.5关闭资源管理器和设备连接——viClose

原型：ViStatus viClose (ViObject vi);

描述：关闭一个资源管理器或者设备连接，并释放内存。

表1-14 viClose函数参数

参数	方向	描述
vi	IN	需要关闭的对象。

表1-15 viClose函数返回值

标识符	值	描述
VI_SUCCESS	0	关闭成功。
VI_WARN_NULL_OBJECT		要关闭的对象时空对象。
VI_ERROR_CLOSING_FAILED		vi不能标识正当对话通道。
VI_ERROR__INV_SESSION VI_ERROR__INV_OBJECT		无法释放与该对话通道相关联的内存数据结构。

2 Labwindows_cvi基于c语言编程

案例：以3672系列的矢量网络分析仪为例，实现矢网连接，发送命令到矢网，接收矢网数据，关闭矢网连接等功能。

2.1界面设计

界面主要包含矢网连接、发送矢网重置命令、接收矢网数据、断开矢网连接、消息提示框等功能。

图2-1 demo界面

2.2实现代码

所有功能实现代码如下：

#include <utility.h>
#include <ansi_c.h>
#include <cvirte.h>		
#include <userint.h>
#include <visa.h> 
#include "PNA_CONECT.h"

static int pnaConect;

ViSession  defaultRM ,vi; 
unsigned char Data_Mag[5000];  // 幅度测试数据 
char c_currentMessage[300];   // 提示消息

void GetDateTime(void);
/*==========VISA资源管理器定位==========*/    
int RMConnect(void);  

int main (int argc, char *argv[])
{
	if (InitCVIRTE (0, argv, 0) == 0)
		return -1;	/* out of memory */
	if ((pnaConect = LoadPanel (0, "PNA_CONECT.uir", PNA_CONECT)) < 0)
		return -1;
	DisplayPanel (pnaConect);
	RunUserInterface ();
	DiscardPanel (pnaConect);
	return 0;
}

int CVICALLBACK PNA_CONECT_CALLBACK (int panel, int event, void *callbackData,
									 int eventData1, int eventData2)
{
	switch (event)
	{
		case EVENT_GOT_FOCUS:

			break;
		case EVENT_LOST_FOCUS:

			break;
		case EVENT_CLOSE:
			 QuitUserInterface (0);
			break;
	}
	return 0;
}

/*==========VISA资源管理器定位==========*/   
int RMConnect()
{
	 	int error,result; 
		error=	viOpenDefaultRM(&defaultRM);
		while(error)
		{
			result = GenericMessagePopup("Error", "VISA资源管理器定位失败！", "重试", "忽略", "", 0, 0, 0, VAL_GENERIC_POPUP_BTN1, VAL_GENERIC_POPUP_BTN1, VAL_GENERIC_POPUP_NO_CTRL);
			if(result==1)
			{
				 error=	viOpenDefaultRM(&defaultRM);
			}
			else
				break;
		}
	    return defaultRM;
}


/* 连接矢网 */ 
int CVICALLBACK ConnectPna_CALLBACK (int panel, int control, int event,
									 void *callbackData, int eventData1, int eventData2)
{
	int error, select; 
	switch (event)
	{
		case EVENT_COMMIT:
			   
			RMConnect();
			error =  viOpen(defaultRM, "TCPIP0::192.168.1.41::5025::SOCKET", VI_NULL,VI_NULL, &vi); //3672B
			
			if(error==0)
			{
					  GetDateTime()  ;
					  strcat(c_currentMessage," 矢网连接成功！\n");
					  SetCtrlVal (panel, PNA_CONECT_TEXTBOX, c_currentMessage); 
			}
			while ( error )
			{
				select= GenericMessagePopup ("Error", "矢网连接错误，请重试或检查连接状态", "重试", "忽略", "", 0, 0, 0, VAL_GENERIC_POPUP_BTN1, VAL_GENERIC_POPUP_BTN1, VAL_GENERIC_POPUP_NO_CTRL);
			
				if ( select == 1 )
				{
				error =  viOpen(defaultRM, "TCPIP0::192.168.1.41::1024::SOCKET", VI_NULL,VI_NULL, &vi);
				}
				else 
				{
					GetDateTime()  ;
					strcat(c_currentMessage," 矢网连接错误，请重试或检查连接状态！\n");		
					SetCtrlVal (panel, PNA_CONECT_TEXTBOX, c_currentMessage);
				}
				break; 
			}
	}
	return vi; 
}

//发送矢网命令
int CVICALLBACK SEND_RST_CALLBACK (int panel, int control, int event,
								   void *callbackData, int eventData1, int eventData2)
{  

	switch (event)
	{
		case EVENT_COMMIT:
			
			// 矢网重置
			viPrintf(vi,"*RST\n"); 	
			// 删除所有测试设置  
			viPrintf(vi,"CALC:PAR:DEL:ALL\n"); 	
			 // 关闭所有窗口
			viPrintf(vi,"DISPlay:WIND OFF\n");
			 // 打开新建窗口  
	  		viPrintf(vi,"DISPlay:WIND1 ON\n");
			 // 定义测试内容  
			 	
	         // 定义测试内容 
			 viPrintf(vi,"CALC1:PAR:DEF:EXT 'mytrace','S21'\n");
			 
			 // 显示测试迹线 
			 viPrintf(vi,"DISPlay:WIND1:TRAC1:FEED 'mytrace'\n");    
			 
       	     // 选定测试迹线     
			 viPrintf(vi,"CALC1:PAR:SEL 'mytrace'\n");	
			 
             // 设置测试类型（对数幅度） 
			 viPrintf(vi,"CALC1:FORM MLOG\n");
			 
			  // 设置扫描类型为段扫描 */       
			  viPrintf(vi,"SENS1:SWE:TYPE SEGM\n");	
			  
			 // 段扫描开始频率 */   
			 viPrintf(vi,"SENS1:SEGM:FREQ:STAR 12GHz\n");
			 
			 // 段扫描终止频率 */ 
			viPrintf(vi, "SENS1:SEGM:FREQ:STOP 12GHz\n"); 
			
			 // 段扫描频率点数 */  
			viPrintf(vi,"SENS1:SEGM:SWE:POIN 1\n");  		
			 
		    GetDateTime();
			strcat(c_currentMessage," 矢网命令已发送！\n");		
			SetCtrlVal (panel, PNA_CONECT_TEXTBOX, c_currentMessage);  
		 
			 
			break;
	}
	return 0;
}
//接收矢网数据
int CVICALLBACK RECEIVE_DATA_CALLBACK (int panel, int control, int event,
									   void *callbackData, int eventData1, int eventData2)
{
	// 频点个数
	int  length=1;  

	switch (event)
	{
		case EVENT_COMMIT:
	
			// 从通道 1 所选测量轨迹中读取格式化数据。 
			viPrintf(vi,"CALC1:DATA? FDATA\n");			
			 
			// 读取矢网测试数据	 length:频点个数
			viRead (vi,Data_Mag ,length*20,VI_NULL);
		
			GetDateTime();
			strcat(c_currentMessage,"  ");
			strcat(c_currentMessage,Data_Mag);	
			//将读取的数据显示	
			SetCtrlVal (panel, PNA_CONECT_TEXTBOX, c_currentMessage);  
			
			GetDateTime();
			strcat(c_currentMessage," 数据读取完成！\n");		
			SetCtrlVal (panel, PNA_CONECT_TEXTBOX, c_currentMessage);  
		
			break;
	}
	return 0;
}
//释放矢网资源 
int CVICALLBACK DISCONNECT_CALLBACK (int panel, int control, int event,
									 void *callbackData, int eventData1, int eventData2)
{
 
	switch (event)
	{
		case EVENT_COMMIT:
		
			viClose(vi); 
			viClose(defaultRM);
		
			GetDateTime();
			strcat(c_currentMessage," 已经释放矢网资源并关闭！\n");		
			SetCtrlVal (panel, PNA_CONECT_TEXTBOX, c_currentMessage);  
			break;
	}
	return 0;
}

//获取系统日期时间
void GetDateTime()
{
	int i_hour, i_minute , i_second ;
	int i_month , i_day , i_year; 
	char c_hour[9], c_minute[3], c_second[3];
	char c_year[10], c_month[3], c_day[3];
	char c_diagonal[2]="/", c_colon[2]=":",c_space[2]=" "; 
	char c_date[19], c_currenttime[9];
   
	
	//获取系统时间
	GetSystemTime(&i_hour,&i_minute , &i_second   );
	//获取系统日期
	GetSystemDate(&i_month,&i_day, &i_year);   
	
	//将int类型数据转为字符串数据
	sprintf(c_hour,"%d",i_hour);
	sprintf(c_minute,"%d",i_minute); 
	sprintf(c_second,"%d",i_second); 
			
	sprintf(c_year,"%d",i_year);
	sprintf(c_month,"%d",i_month); 
	sprintf(c_day,"%d",i_day);
	
	//拼接字符串
	    strcpy(c_date,strcat(strcat(strcat(strcat(c_year,c_diagonal),c_month),c_diagonal),c_day));
	strcpy(c_currenttime,strcat(strcat(strcat(strcat(c_hour,c_colon),c_minute),c_colon),c_second));   
	strcpy(c_currentMessage,strcat(strcat(c_date,c_space),c_currenttime));
}

2.3功能显示

连接的矢量网络分析仪型号时AV3672B矢量网络分析仪，展示功能如下：

图2-2 demo实现效果

Labwindows_cvi is a program-controlled vector network analyzer based on C language

1 Use of the VISA function library in Labwindows_cvi

1.1 Resource Management

1.2 Resource template

1.3 Specific Resource Operations

1.4 VISA common functions

2 Labwindows_cvi基于c语言编程

2.1界面设计

2.2实现代码

2.3功能显示

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