Connector that loops back communication

For the system that connects to the device capable of RS-232/422/485 communication, there may be only one COM port on the PC.

In this case, it is difficult to check communication with serial diagnostic test software, which assumes that the PC has two COM ports.

By making your own connector that loops back communication (loopback connector), you can perform a serial diagnostic test with only one COM port.

[For RS-232C]

<Connector wiring diagram (for 9 pins)>

          ┌─────┐

          │    TxD  3├─┐

          │    RxD  2├─┘

          │    RTS  7├─┐

          │    CTS  8├─┘

          │    DTR  4├─┐

          │    DSR  6├─┘

          └─────┘

<Connector wiring diagram (for 25 pins)>

          ┌─────┐

          │    TxD  2├─┐

          │    RxD  3├─┘

          │    RTS  4├─┐

          │    CTS  5├─┘

          │    DTR 20├─┐

          │    DSR  6├─┘

          └─────┘

[For RS-422A/485]

RS-422A/485 does not define connector pin assignments.
Therefore, the connector pin assignment differs depending on the device used.

There are also CONTEC devices that have a function to loop back communication without a connector by changing the switch settings on the device.

Please check the instruction manual of the device to be used as necessary.