diff --git a/src/framework/Testee.ts b/src/framework/Testee.ts
index d7a2c5a..e53a575 100644
--- a/src/framework/Testee.ts
+++ b/src/framework/Testee.ts
@@ -81,9 +81,9 @@ export class Testee { // TODO unified with testbed interface
         this.name = name;
         this.specification = specification;
         this.timeout = timeout;
-        this.connector = new TestbedFactory(connectionTimeout);
         this.mapper = new SourceMapFactory();
         this.framework = Framework.getImplementation();
+        this.connector = new TestbedFactory(connectionTimeout, (chunk: Buffer) => this.framework.reporter.debug(chunk.toString()));
     }
 
     public bed(target: Target = Target.supervisor): Testbed | void {
diff --git a/src/manage/Uploader.ts b/src/manage/Uploader.ts
index 4547af9..6889416 100644
--- a/src/manage/Uploader.ts
+++ b/src/manage/Uploader.ts
@@ -50,7 +50,7 @@ export class UploaderFactory {
 
 
 export abstract class Uploader extends EventEmitter {
-    abstract upload(compiled: CompileOutput): Promise<Connection>;
+    abstract upload(compiled: CompileOutput, listener?: (chunk: Buffer) => void): Promise<Connection>;
 
     protected removeTmpDir(tmpdir: string): Promise<void> {
         return new Promise((resolve, reject) => {
@@ -109,7 +109,7 @@ export class EmulatorUploader extends Uploader {
         this.args = args;
     }
 
-    upload(compiled: CompileOutput, listener?: (chunk: any) => void): Promise<SubProcess> {
+    upload(compiled: CompileOutput, listener?: (chunk: Buffer) => void): Promise<SubProcess> {
         return this.connectSocket(compiled.file, listener);
     }
 
@@ -118,7 +118,7 @@ export class EmulatorUploader extends Uploader {
         return spawn(this.interpreter, _args);
     }
 
-    private connectSocket(program: string, listener?: (chunk: any) => void): Promise<SubProcess> {
+    private connectSocket(program: string, listener?: (chunk: Buffer) => void): Promise<SubProcess> {
         const that = this;
         const process = this.startWARDuino(program);
 
@@ -139,7 +139,7 @@ export class EmulatorUploader extends Uploader {
                 const reader = new ReadlineParser();
                 process.stdout.pipe(reader);
 
-                reader.on('data', (data) => {
+                reader.on('data', (data: Buffer) => {
                     if (listener !== undefined) {
                         listener(data);
                     }
diff --git a/src/reporter/Reporter.ts b/src/reporter/Reporter.ts
index 996c444..2a235c2 100644
--- a/src/reporter/Reporter.ts
+++ b/src/reporter/Reporter.ts
@@ -138,4 +138,10 @@ export class Reporter {
     error(text: string) {
         this.output += `error: ${text}\n`;
     }
+
+    debug(text: string) {
+        if (this.verboseness === Verbosity.debug) {
+            console.debug(text);
+        }
+    }
 }
\ No newline at end of file
diff --git a/src/testbeds/Platform.ts b/src/testbeds/Platform.ts
index 7142f3b..114389b 100644
--- a/src/testbeds/Platform.ts
+++ b/src/testbeds/Platform.ts
@@ -81,10 +81,12 @@ export abstract class Platform extends EventEmitter implements Testbed {
 
     // send request over duplex channel
     public sendRequest<R>(map: SourceMap.Mapping, request: Request<R>): Promise<R> {
+        const message = `${request.type}${request.payload?.(map) ?? ''}\n`;
+        this.emit(TestbedEvents.Send, message);
         return new Promise((resolve, reject) => {
             this.requests.push([request, resolve]);
-            this.connection.channel.write(`${request.type}${request.payload?.(map) ?? ''}\n`, (err: any) => {
-                if (err !== null) {
+            this.connection.channel.write(message, (err: Error | null | undefined) => {
+                if (err !== null && err !== undefined) {
                     reject(err);
                 }
             });
diff --git a/src/testbeds/Testbed.ts b/src/testbeds/Testbed.ts
index 96a535e..25cc7d3 100644
--- a/src/testbeds/Testbed.ts
+++ b/src/testbeds/Testbed.ts
@@ -8,7 +8,8 @@ export enum TestbedEvents {
     OnMessage = 'message',
     OnBreakpointHit = 'breakpoint',
     OnPushEvent = 'push',
-    Ready = 'ready'
+    Ready = 'ready',
+    Send = 'send'
 }
 
 export declare interface Testbed extends EventEmitter {
@@ -25,4 +26,8 @@ export declare interface Testbed extends EventEmitter {
     on(event: TestbedEvents.OnBreakpointHit, listener: (message: Breakpoint) => void): this;
 
     on(event: TestbedEvents.OnPushEvent, listener: (data: string) => void): this;
+
+    on(event: TestbedEvents.Ready, listener: (data: string) => void): this;
+
+    on(event: TestbedEvents.Send, listener: (data: string) => void): this;
 }
diff --git a/src/testbeds/TestbedFactory.ts b/src/testbeds/TestbedFactory.ts
index 39861a8..fa0c31b 100644
--- a/src/testbeds/TestbedFactory.ts
+++ b/src/testbeds/TestbedFactory.ts
@@ -1,4 +1,4 @@
-import {Testbed} from './Testbed';
+import {Testbed, TestbedEvents} from './Testbed';
 import {ARDUINO, EMULATOR, WABT} from '../util/env';
 import {CompileOutput, CompilerFactory} from '../manage/Compiler';
 import {DummyProxy, Emulator} from './Emulator';
@@ -13,28 +13,36 @@ export class TestbedFactory {
     public readonly timeout: number;
     private readonly compilerFactory: CompilerFactory;
     private readonly uploaderFactory: UploaderFactory;
+    private readonly listener?: (chunk: Buffer) => void;
 
-    constructor(timeout: number) {
+    constructor(timeout: number, listener?: (chunk: Buffer) => void) {
         this.timeout = timeout;
+        this.listener = listener;
         this.compilerFactory = new CompilerFactory(WABT);
         this.uploaderFactory = new UploaderFactory(EMULATOR, ARDUINO);
     }
 
     public async initialize(specification: TestbedSpecification, program: string, args: string[]): Promise<Testbed> {
         const compiled: CompileOutput = await this.compilerFactory.pickCompiler(program).compile(program).catch((e) => Promise.reject(e));
-        const connection: Connection = await this.uploaderFactory.pickUploader(specification, args).upload(compiled).catch((e) => Promise.reject(e));
+        const connection: Connection = await this.uploaderFactory.pickUploader(specification, args).upload(compiled, this.listener).catch((e) => Promise.reject(e));
 
+        let testbed: Testbed;
         switch (specification.type) {
             case PlatformType.arduino:
-                return new Arduino(connection as Serial);
+                testbed = new Arduino(connection as Serial);
+                break;
             case PlatformType.emulator:
             case PlatformType.emu2emu:
             case PlatformType.debug:
-                return new Emulator(connection as SubProcess);
+                testbed = new Emulator(connection as SubProcess);
+                break;
             case PlatformType.emuproxy:
-                return new DummyProxy(connection as SubProcess, specification as ProxySpecification);
+                testbed = new DummyProxy(connection as SubProcess, specification as ProxySpecification);
+                break;
             default:
                 return Promise.reject('Platform not implemented.');
         }
+        testbed.on(TestbedEvents.Send, (message: string) => this.listener?.(Buffer.from(message)));
+        return testbed;
     }
 }