A CMG DB9 Null Modem M-M Cable is used to directly connect two devices that both behave like “data terminal equipment” (DTE), typically for serial communication.

Here’s what that means in practice:

What “null modem” does

A normal serial cable connects a computer (DTE) to something like a modem (DCE). A null modem cable “crosses” the transmit and receive lines so two computers (or similar devices) can talk directly to each other without a modem.

What “DB9 M-M” means

• DB9: 9-pin serial connector (common RS-232 port)
• M-M (male-to-male): Both ends have male connectors

Typical uses

You’d use this cable for things like:

• Connecting two computers via serial ports (older systems)
• Configuring network equipment (routers, switches, firewalls) through a console port
• Data transfer between embedded systems or industrial devices
• Debugging or maintenance on servers or legacy hardware

Common scenarios

• Linking two PCs to transfer files (pre-USB era or specialized setups)
• Connecting to devices from companies like Cisco via a console port
• Interfacing with lab equipment, CNC machines, or other serial-controlled hardware