DB9 RS-232 Mini Tester with LED Indicators

What is this DB9 RS232 mini tester LED troubleshooting tool?
This is an RS232 mini tester that can be used to troubleshoot bad cables, connections, improper operation of computer or CNC and more. Even if you do not fully understand how to use it you can compare operation on machines working normally and test between cables.

Features
DB9 Male to Female Pass Through M/F RS-232 V.24 Serial Mini-Tester
Serial Troubleshooting
Non Intrusive For DB9 Data Signal Indication
Serial Tracing SignalsTD

• RTS
• DSR
• CD
• RD
• CTS
• DTR