PI API 基础函数（一）

【Wee_Wong 原创文章，转载请注明出处】

首先介绍一下PI API 函数的命名规则，熟悉了PI API的命名规则，在使用时会比较清楚需要使用哪类函数。

PI API中函数都是以pi开头后接函数的类别，最后跟着函数名（以函数实现的功能命名）

如：

Archive Functions 存档函数：命名规则为：piar_

PI Batch Functions 作业函数：命名规则为：piba_

Event Log Functions事件日志：命名规则为：piel_

PI Login Functions连接管理：命名规则为：pilg_(Message Log Functions 也是以此开头)

Point Database Functions测点属性：命名规则为：pipt_

Snapshot Functions快照函数：命名规则为：pisn_

Time Functions时间函数：命名规则为：pitm_

Utility Functions 基本信息：命名规则为：piut_

其中标红的代表这些函数比较常用， 大多数函数都是以返回0代表函数调用成功！

以下是连接PI，获取PI服务器基本信息的函数，如下表：

函数名称	英文解释	Utility Functions 解释
piut_connect	Establish a remote connection with the pi Server	建立与 pi 服务器的远程连接
piut_disconnect	Close all remote connections with PI Servers	关闭与 PI 的服务器的所有远程连接
piut_disconnectnode	Close remote connection with passed node	关闭远程连接与传递节点
piut_getapiversion	Get the current API version number	获取当前的 API 版本数
piut_getprofile	Get a value for an entry and section in an initialization file	获取一个值，用于输入和初始化文件中的节
piut_getprotocolvers	Get the PI Server protocol version	获取 PI 服务器协议版本
piut_getserverversion	Obtain version information about the current server	获取有关当前服务器的版本信息
piut_inceventcounter	Increment an event counter	增量事件计数器
piut_ishome	Determines if this is a pi home node	确定是否这是 pi 主节点
piut_login	Gain access to protected PI data	访问受保护的 PI 数据
piut_netinfo	Get local network information	获取本地网络信息
piut_netnodeinfo	Get network information for the passed node name	获取网络信息传递的节点名称
piut_netserverinfo	Get network information for the default server	获取默认的服务器的网络信息
piut_setdefaultservernode	Set the current server to the default server	将当前的服务器设置为默认的服务器
piut_setprocname	Set the process name to specified name	设置为指定名称的进程的名称
piut_setservernode	Set the current server to a specified node	将当前的服务器设置为指定的节点
piut_writeprofile	Write a value for an entry and section into an initialization file	一个值，用于输入和部分写入初始化文件
piut_zeroeventcounter	Zero an event counter	零事件计数器

其中piut_setservernode 和piut_login为主要使用的函数，简单介绍一下这两个函数

piut_setservernode 连接PI服务器使用，传入服务器地址即可。

This function sets the active PI Server node where the data for the subsequent PI-API calls will be resolved. Passing a NULL server string will result in resetting to the default server. The first time a server is specified, there may be a delay as a connection is established. The number of concurrently active servers is limited by the network protocol being used, the operating system, and the hardware platform.

C format

int32 piut_setservernode(

char PIPTR * servername );

Returns

>0	System Error (typically network related)
0	Success
-1	Server name is not the same as the PI Home node (DEC VAX only)

Arguments

servername(passed)

Name of the PI Server node

piut_login

传入用户名、密码，输出参数返回该用户的权限

This function establishes a user's access to PI System data based on a login to a configured user database (PI User Database or VMS UAF) The login call may be made in one of two ways: by passing a NULL string for the username argument and a NULL string for the password argument, the server will return the default level of access, or by passing a username and password and attempting to qualify a valid login. Note that a null string is a valid pointer to an array of chars whose first element is set to 0. This requirement is distinctly different from pilg_login which accepts NULL pointers.

If piut_login is called after a valid login was performed, the request is ignored and the existing authorization level is returned invalid. See the Usage Notes for interpretation of thevalidparameter.

C format

int32 piut_login(

char PIPTR * username,

char PIPTR * passwrd,

int32 PIPTR * valid );

Returns

>0	System error
0	Success
-999	Login error

Arguments

username (passed)

Null terminated character string

passwrd (passed)

Null terminated password string

valid (returned)

Level of access available

#define PINO 0 无权限

#define PIREAD 1只读

#define PIREADWRITE 2读写

基本函数就先介绍到此了,其他的函数会在以后的章节讲解。

【Wee_Wong 原创文章，转载请注明出处】