jsmodebus

2019-01-16 12:38:53 +08:00
parent 36025dac53
commit 935d418fe3
25 changed files with 2079 additions and 0 deletions
@@ -0,0 +1,145 @@
+'use strict';
+
+const Stampit         = require('stampit');
+const StateMachine    = require('stampit-state-machine');
+const EventBus = require('stampit-event-bus');
+
+const ExceptionMessage = {
+    0x01: 'ILLEGAL FUNCTION',
+    0x02: 'ILLEGAL DATA ADDRESS',
+    0x03: 'ILLEGAL DATA VALUE',
+    0x04: 'SLAVE DEVICE FAILURE',
+    0x05: 'ACKNOWLEDGE',
+    0x06: 'SLAVE DEVICE BUSY',
+    0x08: 'MEMORY PARITY ERROR',
+    0x0A: 'GATEWAY PATH UNAVAILABLE',
+    0x0B: 'GATEWAY TARGET DEVICE FAILED TO RESPOND'
+};
+
+module.exports = Stampit()
+    .compose(StateMachine, EventBus)
+    .init(function () {
+        this.log = this.options && this.options.log;
+
+        if (!this.log) {
+            this.log =  {
+                log:   () => console.log.apply(console, arguments),
+                error: () => console.error.apply(console, arguments),
+                warn:  () => console.warn.apply(console, arguments),
+                debug: () => console.log.apply(console, arguments)
+            };
+        }
+
+        let responseHandler = {};
+        let currentRequest  = null;
+
+        let reqFifo = [];
+
+        let init = () => {
+            this.options.timeout = this.options.timeout || (5 * 1000); // 5s
+
+            this.on('data', onData);
+            this.on('newState_ready', flush);
+            this.on('newState_closed', onClosed);
+        };
+
+        let flush = () => {
+            if (reqFifo.length) {
+                currentRequest = reqFifo.shift();
+
+                currentRequest.timeout = setTimeout(() => {
+                    currentRequest.cb && currentRequest.cb({err: 'timeout'});
+                    this.emit('trashCurrentRequest');
+                    this.log.error('Request timed out.');
+                    this.setState('error');
+                }, this.options.timeout);
+
+                this.setState('waiting');
+                this.emit('send', currentRequest.pdu, currentRequest.unitId);
+            }
+        };
+
+        let onClosed = () => {
+            if (currentRequest) {
+                this.log.debug('Clearing timeout of the current request.');
+                clearTimeout(currentRequest.timeout);
+            }
+
+            this.log.debug('Cleaning up request fifo.');
+            reqFifo = [];
+        };
+
+        let handleErrorPDU = (pdu) => {
+            const errorCode = pdu.readUInt8(0);
+
+            // if error code is smaller than 0x80
+            // ths pdu describes no error
+
+            if (errorCode < 0x80) {
+                return false;
+            }
+
+            // pdu describes an error
+            const exceptionCode = pdu.readUInt8(1);
+            const message = ExceptionMessage[exceptionCode];
+
+            const err = {
+                errorCode:      errorCode,
+                exceptionCode:  exceptionCode,
+                message:        message
+            };
+
+            // call the desired deferred
+            currentRequest.cb && currentRequest.cb(err);
+
+            return true;
+        };
+
+        /**
+          *  Handle the incoming data, cut out the mbap
+          *  packet and send the pdu to the listener
+          */
+        let onData = (pdu, unitId) => {
+            if (!currentRequest) {
+                this.log.debug('No current request.');
+                return;
+            }
+
+            clearTimeout(currentRequest.timeout);
+
+            // check pdu for error
+            if (handleErrorPDU(pdu)) {
+                this.log.debug('Received pdu describes an error.');
+                currentRequest = null;
+                this.setState('ready');
+                return;
+            }
+
+            // handle pdu
+
+            const handler = responseHandler[currentRequest.fc];
+            if (!handler) {
+                this.log.debug(`Found no handler for fc ${currentRequest.fc}`);
+                throw new Error(`No handler implemented for fc ${currentRequest.fc}`);
+            }
+
+            handler(unitId, pdu, currentRequest.cb);
+
+            this.setState('ready');
+        };
+
+        this.addResponseHandler = (fc, handler) => {
+            responseHandler[fc] = handler;
+            return this;
+        };
+
+        this.queueRequest = (unitId, fc, pdu, cb) => {
+            reqFifo.push({unitId, fc, pdu, cb});
+
+            if (this.inState('ready')) {
+                flush();
+            }
+        };
+
+        init();
+    });