jsmodebus

lib/jsmodbus/handler/server/WriteMultipleCoils.js

@@ -0,0 +1,77 @@
+'use strict';
+
+const Stampit = require('stampit');
+const Put     = require('put');
+
+module.exports = Stampit()
+    .init(function () {
+        const FC = 15;
+        let init = () => {
+            this.log.debug('initiating write multiple coils request handler.');
+            this.responseDelay = this.responseDelay || 0;
+            this.setRequestHandler(FC, onRequest);
+        };
+
+        let _onRequest = (pdu, cb) => {
+            this.log.debug('handling write multiple coils request.');
+
+            if (pdu.length < 3) {
+                cb(Put().word8(0x8F).word8(0x02).buffer());
+            } else {
+                // const fc        = pdu.readUInt8(0);
+                const start     = pdu.readUInt16BE(1);
+                const quantity  = pdu.readUInt16BE(3);
+                const byteCount = pdu.readUInt8(5);
+
+                this.emit('preWriteMultipleCoilsRequest', start, quantity, byteCount);
+
+                let mem = this.getCoils();
+
+                // error response
+                if (!quantity || start + quantity > mem.length * 8) {
+                    cb(Put().word8(0x8F).word8(0x02).buffer());
+                } else {
+                    let response = Put().word8(0x0F).word16be(start).word16be(quantity).buffer();
+                    let oldValue;
+                    let newValue, current = pdu.readUInt8(6);
+                    let j = 0;
+
+                    for (let i = start; i < start + quantity; i += 1) {
+                        // reading old value from the coils register
+                        oldValue = mem.readUInt8(Math.floor(i / 8));
+
+                        // apply new value
+                        if ((Math.pow(2, j % 8) & current)) {
+                            newValue = oldValue | Math.pow(2, i % 8);
+                        } else {
+                            newValue = oldValue & ~Math.pow(2, i % 8);
+                        }
+
+                        // write to buffer
+                        mem.writeUInt8(newValue, Math.floor(i / 8));
+
+                        // read new value from request pdu
+                        j += 1;
+
+                        if (j % 8 === 0 && j < quantity) {
+                            current = pdu.readUInt8(6 + Math.floor(j / 8));
+                        }
+                    }
+
+                    this.emit('postWriteMultipleCoilsRequest', start, quantity, byteCount);
+
+                    cb(response);
+                }
+            }
+        };
+
+        let onRequest = (pdu, cb) => {
+            if (this.responseDelay) {
+                setTimeout(_onRequest, this.responseDelay, pdu, cb);
+            } else {
+                setImmediate(_onRequest, pdu, cb);
+            }
+        };
+
+        init();
+    });