Initial commit

lib/jsmodbus/handler/server/WriteSingleRegister.js

@@ -0,0 +1,50 @@
+'use strict';
+
+const Stampit = require('stampit');
+const Put     = require('put');
+
+module.exports = Stampit()
+    .init(function () {
+        const FC = 6;
+        let init = () => {
+            this.log.debug('initiating write single register request handler.');
+            this.responseDelay = this.responseDelay || 0;
+            this.setRequestHandler(FC, onRequest);
+        };
+    
+        let _onRequest = (pdu, cb) => {
+            this.log.debug('handling write single register request.');
+
+            if (pdu.length !== 5) {
+                cb(Put().word8(0x86).word8(0x02).buffer());
+            } else {
+                // const fc          = pdu.readUInt8(0);
+                const address     = pdu.readUInt16BE(1);
+                const byteAddress = address * 2;
+                const value       = pdu.readUInt16BE(3);
+
+                this.emit('preWriteSingleRegisterRequest', byteAddress, value);
+
+                let mem = this.getHolding();
+
+                if (byteAddress + 2 > mem.length) {
+                    cb(Put().word8(0x86).word8(0x02).buffer());
+                } else {
+                    let response = Put().word8(0x06).word16be(address).word16be(value).buffer();
+                    mem.writeUInt16BE(value, byteAddress);
+                    this.emit('postWriteSingleRegisterRequest', byteAddress, value);
+                    cb(response);
+                }
+            }
+        };
+
+        let onRequest = (pdu, cb) => {
+            if (this.responseDelay) {
+                setTimeout(_onRequest, this.responseDelay, pdu, cb);
+            } else {
+                setImmediate(_onRequest, pdu, cb);
+            }
+        };
+
+        init();
+    });