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TCP and UDP debugging
Serial-to-network modules and gateways often need both sides checked together.
- TCP Client: connect to a device, gateway or test server.
- TCP Server: listen locally and observe incoming clients.
- UDP: test datagram-based protocols, broadcast-like discovery or gateway forwarding.
- Hex mode: use it for binary payloads over TCP or UDP, not only for serial ports.
- Indicator lamps: a TCP/UDP connection keeps only the TX/RX activity pair; the six serial control-line lamps hide automatically.
- Tx counter: it only counts bytes the transport actually accepted. While a TCP server has no connected client, sending neither increases the Tx counter nor blinks the TX lamp — a quick way to tell whether data really left the application.
- Logs: save network-side traffic when comparing it with serial-side traffic.
When TCP or UDP fails, check IP address, port, firewall rules, subnet, gateway mode and whether another process already holds the same local port.
Sharing a serial port over the network with RFC 2217 — including working with a port on a remote device server — is covered in Remote serial ports (RFC 2217).