node.js - Node opc-ua - 我如何发现服务器中的变量？

Question

我正在学习 Node opc-ua 并遵循 GitHub 页面中为 sample_server.js 和 simple_client.js 提供的示例。

在sample_server中我在构建服务器地址空间的时候添加了一个变量比如:

//this code is in the server    
addressSpace.addVariable({
        componentOf: device,
        nodeId: "ns=1;s=variable_1",
        browseName: "MyVariable1",
        dataType: "Double",
        value: {
            get: function () {
                return new opcua.Variant({ dataType: opcua.DataType.Double, value: variable1 });
            }
        }
    });

这里是整个服务器代码供引用:

var opcua = require("node-opcua");

var server = new opcua.OPCUAServer({
    port: 4334, // the port of the listening socket of the server
    resourcePath: "UA/MyLittleServer", // this path will be added to the endpoint resource name
    buildInfo: {
        productName: "MySampleServer1",
        buildNumber: "7658",
        buildDate: new Date(2014, 5, 2)
    }
});

server.initialize(post_initialize);

function post_initialize() {
    console.log("initialized");
    construct_my_address_space(server, function () {
        server.start(function () {
            console.log("Server is now listening ... ( press CTRL+C to stop)");
            console.log("port ", server.endpoints[0].port);
            var endpointUrl = server.endpoints[0].endpointDescriptions()[0].endpointUrl;
            console.log(" the primary server endpoint url is ", endpointUrl);
        });
    });

}

function construct_my_address_space(server, callback) {

    var addressSpace = server.engine.addressSpace;

    // declare a new object
    var device = addressSpace.addObject({
        organizedBy: addressSpace.rootFolder.objects,
        browseName: "MyDevice"
    });

    // add a variable named MyVariable1 to the newly created folder "MyDevice"
    var variable1 = 1;

    // emulate variable1 changing every 500 ms
    setInterval(function () { variable1 += 1; }, 500);

    addressSpace.addVariable({
        componentOf: device,
        nodeId: "ns=1;s=variable_1",
        browseName: "MyVariable1",
        dataType: "Double",
        value: {
            get: function () {
                return new opcua.Variant({ dataType: opcua.DataType.Double, value: variable1 });
            }
        }
    });

    callback();
}

现在，在客户端中，我想通过名称或完整的 nodeId 来发现这个变量。我正在使用提供的示例浏览到服务器的 session ，但在返回时我只看到 FolderType、Objects、Types 和 Views，无法在任何地方找到这个变量。

这是客户端代码:

var opcua = require("node-opcua");
var async = require("async");

var client = new opcua.OPCUAClient();
var endpointUrl = "opc.tcp://" + require("os").hostname() + ":4334/UA/MyLittleServer";

var the_session, the_subscription;

async.series([

    // step 1 : connect to
    function (callback) {
        client.connect(endpointUrl, function (err) {
            if (err) {
                console.log(" cannot connect to endpoint :", endpointUrl);
            } else {
                console.log("connected !");
            }
            callback(err);
        });
    },

    // step 2 : createSession
    function (callback) {
        client.createSession(function (err, session) {
            if (!err) {
                the_session = session;
            }
            callback(err);
        });
    },

    // step 3 : browse
    function (callback) {
        the_session.browse("RootFolder", function (err, browse_result) {
            if (!err) {
                console.log('Result of browsing: ', browse_result);
                browse_result[0].references.forEach(function (reference) {
                    console.log('browsing: ', reference.browseName);
                    console.log(reference);
                    console.log("**************************************");
                });
            }
            callback(err);
        });
    },

    /* step 4 : read a variable with readVariableValue
    function (callback) {
        the_session.readVariableValue("ns=1;s=variable_1", function (err, dataValue) {
            if (!err) {
                console.log(" var 1 = ", dataValue.toString());
            }
            callback(err);
        });
    },

    // step 4' : read a variable with read
    function (callback) {
        var max_age = 0;
        var nodes_to_read = [
            { nodeId: "ns=1;s=variable_1", attributeId: opcua.AttributeIds.Value }
        ];
        the_session.read(nodes_to_read, max_age, function (err, nodes_to_read, dataValues) {
            if (!err) {
                console.log(" variable 1 = ", dataValues[0]);
            }
            callback(err);
        });
    },
    */
    // step 5: install a subscription and install a monitored item for 10 seconds
    function (callback) {
        the_subscription = new opcua.ClientSubscription(the_session, {
            requestedPublishingInterval: 1000,
            requestedLifetimeCount: 10,
            requestedMaxKeepAliveCount: 2,
            maxNotificationsPerPublish: 10,
            publishingEnabled: true,
            priority: 10
        });

        the_subscription.on("started", function () {
            console.log("subscription started for 2 seconds - subscriptionId=", the_subscription.subscriptionId);
        }).on("keepalive", function () {
            console.log("keepalive");
        }).on("terminated", function () {
            callback();
        });

        setTimeout(function () {
            the_subscription.terminate();
        }, 10000);

        // install monitored item
        var monitoredItem = the_subscription.monitor({
            nodeId: opcua.resolveNodeId("ns=1;s=variable_1"),
            attributeId: opcua.AttributeIds.Value
        },
            {
                samplingInterval: 100,
                discardOldest: true,
                queueSize: 10
            },
            opcua.read_service.TimestampsToReturn.Both
        );
        console.log("-------------------------------------");

        monitoredItem.on("changed", function (dataValue) {
            console.log("variable_1 = ", dataValue.value.value);
        });
    },

    // close session
    function (callback) {
        the_session.close(function (err) {
            if (err) {
                console.log("session closed failed ?");
            } else{
                console.log("session closed!");
            }
            callback();
        });
    }

],
    function (err) {
        if (err) {
            console.log(" failure ", err);
        } else {
            console.log("done!");
        }
        client.disconnect(function () { });
    });

提前致谢

Answer 1

您需要从根文件夹向下钻取并调查各种对象，直到找到您要监视的变量，以及一系列浏览 Node 。最好的选择是使用来自商业供应商的免费 OPCUA 客户端，例如 UAExpert或 Prosys OPC UA Client仅举几例。

您还可以使用 opcua-commander:这个小实用程序将允许您探索服务器的地址空间并找到您正在寻找的 Node 。 (源代码可在 github 上找到)