jsmodebus

lib/jsmodbus/handler/server/WriteSingleCoil.js

@@ -0,0 +1,62 @@
+'use strict';
+
+const Stampit = require('stampit');
+const Put     = require('put');
+
+module.exports = Stampit()
+    .init(function () {
+        const FC = 5;
+        let init = () => {
+            this.log.debug('initiating write single coil request handler.');
+            this.responseDelay = this.responseDelay || 0;
+            this.setRequestHandler(FC, onRequest);
+        };
+    
+        let _onRequest = (pdu, cb) => {
+            if (pdu.length !== 5) {
+                cb(Put().word8(0x85).word8(0x02).buffer());
+            } else {
+                // const fc      = pdu.readUInt8(0);
+                const address = pdu.readUInt16BE(1);
+                const value   = (pdu.readUInt16BE(3) === 0x0000);
+
+                if (pdu.readUInt16BE(3) !== 0x0000 && pdu.readUInt16BE(3) !== 0xFF00) {
+                    cb(Put().word8(0x85).word8(0x03).buffer());
+                } else {
+                    this.emit('preWriteSingleCoilRequest', address, value);
+
+                    let mem = this.getCoils();
+
+                    if (address + 1 > mem.length * 8) {
+                        cb(Put().word8(0x85).word8(0x02).buffer());
+                    } else {
+                        let response = Put().word8(0x05).word16be(address).word16be(value ? 0xFF00 : 0x0000);
+                        let oldValue = mem.readUInt8(Math.floor(address / 8));
+                        let newValue;
+
+                        if (value) {
+                            newValue = oldValue | Math.pow(2, address % 8);
+                        } else {
+                            newValue = oldValue & ~Math.pow(2, address % 8);
+                        }
+
+                        mem.writeUInt8(newValue, Math.floor(address / 8));
+
+                        this.emit('postWriteSingleCoilRequest', address, value);
+
+                        cb(response.buffer());
+                    }
+                }
+            }
+        };
+
+        let onRequest = (pdu, cb) => {
+            if (this.responseDelay) {
+                setTimeout(_onRequest, this.responseDelay, pdu, cb);
+            } else {
+                setImmediate(_onRequest, pdu, cb);
+            }
+        };
+
+        init();
+    });