Initial commit

lib/jsmodbus/handler/client/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.addResponseHandler(FC, onResponse);
+
+        let onResponse = (unitId, pdu, cb) => {
+            const fc              = pdu.readUInt8(0);
+            const registerAddress = pdu.readUInt16BE(1);
+            const registerValue   = pdu.readUInt16BE(3);
+
+            let resp = {
+                unitId:             unitId,
+                fc:                 fc,
+                registerAddress:    registerAddress,
+                registerValue:      registerValue,
+                registerAddressRaw: pdu.slice(1,2),
+                registerValueRaw:   pdu.slice(3,2)
+            };
+
+            if (fc !== FC) {
+                cb(`WriteSingleRegister: Invalid FC ${fc}`);
+            } else {
+                cb(null, resp);
+            }
+        };
+
+        this.writeSingleRegister = (unitId, address, value) => {
+            return new Promise((resolve, reject) => {
+                const payload = (value instanceof Buffer) ? value : Put().word16be(value).buffer();
+                const pdu     = Put().word8be(FC).word16be(address).put(payload);
+
+                this.queueRequest(unitId, FC, pdu.buffer(), (err, resp) => {
+                    if (err) {
+                        reject(err);
+                    } else {
+                        resolve(resp);
+                    }
+                });
+            });
+        };
+
+        init();
+    
+    });