using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using SAPFunctionsOCX;
using SAPLogonCtrl;
using SAPTableFactoryCtrl;

namespace SAPFunction
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

      
        private void BtnConn_Click(object sender, EventArgs e)
        {  
               //设置登录连接的类
                DataSet dset = new DataSet();
                SAPLogonCtrl.SAPLogonControlClass logon = new SAPLogonCtrl.SAPLogonControlClass();
                //连接参数设置
                logon.ApplicationServer = "172.18.95.173";
                logon.Client = "164";
                logon.Language = "ZH";
                logon.User = "CRMDEV69";
                logon.Password = "654321";
                logon.SystemNumber = 7;
               
                //实例化连接对象
                SAPLogonCtrl.Connection Conn;

                Conn = (SAPLogonCtrl.Connection)logon.NewConnection();
                //Conn.CodePage = "8400";
                //调用登录方法
                if (Conn.Logon(0, true))
                {
                    label1.Text = "登录成功!";
                }

               //实例SAPFunction对象

                SAPFunctionsOCX.SAPFunctionsClass func = new SAPFunctionsClass();

                //设置连接
                func.Connection = Conn;
               
                SAPFunctionsOCX.IFunction ifunc = (SAPFunctionsOCX.IFunction)func.Add("ZCSMS_GET_HRINFO");
                //设置输入参数
                SAPFunctionsOCX.IParameter BEGDAFROM = (SAPFunctionsOCX.IParameter)ifunc.get_Exports("BEGDAFROM");
                BEGDAFROM.Value = "";
                SAPFunctionsOCX.IParameter BEGDATO = (SAPFunctionsOCX.IParameter)ifunc.get_Exports("BEGDATO");
                BEGDATO.Value = "";
                SAPFunctionsOCX.IParameter MILL = (SAPFunctionsOCX.IParameter)ifunc.get_Exports("MILL");
                MILL.Value = "7960";
                SAPFunctionsOCX.IParameter NUMBERFROM = (SAPFunctionsOCX.IParameter)ifunc.get_Exports("NUMBERFROM");
                NUMBERFROM.Value = "0061500001";
                SAPFunctionsOCX.IParameter NUMBERTO = (SAPFunctionsOCX.IParameter)ifunc.get_Exports("NUMBERTO");
                NUMBERTO.Value = "0061500020";
                //调用RFC方法
                ifunc.Call();
                SAPTableFactoryCtrl.Tables ENQs = (SAPTableFactoryCtrl.Tables)ifunc.Tables;
                SAPTableFactoryCtrl.Table ENQ = (SAPTableFactoryCtrl.Table)ENQs.get_Item("THR");

                int j = ENQ.RowCount;
                DataTable dt = new DataTable();
                for (int i = 1 ;i<=ENQ.RowCount; i ++)
                {
                    DataRow dr = dt.NewRow();
                    if (i == 1)
                    {
                        dt.Columns.Add("MILL");
                        dt.Columns.Add("PERNR");
                        dt.Columns.Add("NAME1");
                        dt.Columns.Add("STEXT");
                    }
                   
                    dr["MILL"] = (String)ENQ.get_Value(i, "MILL");
                    dr["PERNR"] = (String)ENQ.get_Value(i, "PERNR");
                    dr["NAME1"] = (String)ENQ.get_Value(i, "NAME1");
                    dr["STEXT"] = (String)ENQ.get_Value(i, "STEXT");
                    dt.Rows.Add(dr);
                }
                dataGridView1.DataSource = dt.DefaultView; 
        }  
    }
}

当然， RFC连接SAP只是其中的方法之一， BAPI等多种方式.