Logbook link (Hamlib rigctl)

Radio Remote can let a logbook program on another computer follow the radio: the logbook shows the frequency and mode, and fills them into a new contact automatically. It can also change the frequency and mode when you click a spot or a bandmap entry.

It speaks Hamlib's "NET rigctl" protocol on TCP port 4532, which Log4OM, N1MM+, CQRLOG, HamRS, Ham Radio Deluxe and many others understand. The program on the other computer does not need a COM port or a USB cable: it connects to the Pi over the network.

What it can and cannot do


Read frequency, mode, split, whether the radio is transmitting	yes
Set frequency and mode	yes (can be switched to read-only)
Transmit (PTT)	never: a PTT-on request is refused and logged, even when transmitting is enabled in Admin > Config
Switch the radio off	never
Change frequency or mode while the radio transmits	refused

This is a deliberate limit: the link has no password (the protocol has none), so it can only do harmless things. WSJT-X and other programs that need to transmit through the radio are not supported by this link.

Switch it on

Sign in as an administrator, Admin > Config > Logbook link.
Tick Switch the logbook link on and press Apply. It starts at once (no restart).
The card now says Listening on port 4532 and shows which computers are connected.

Settings in the card:

Let the logbook change frequency and mode: untick it for a read-only link.
Port: 4532 is the usual one. Change it only if something else uses it.
Allowed addresses: private (the default) means this Pi and the usual home-network ranges (192.168.x.x, 10.x.x.x, 172.16-31.x.x). Computers anywhere else are dropped without an answer. To allow one computer or a Tailscale address use a list, for example 192.168.1.40, 100.64.0.0/10.

Never forward port 4532 on your router. Anyone who could reach it could retune the radio. Keep it for the home network (or Tailscale).

Log4OM

In Log4OM open Settings > Program Configuration > Hardware Configuration and add a new radio / CAT interface.
Choose Hamlib as the interface and, as the radio model, NET rigctl (Hamlib model 2, sometimes listed as "Hamlib NET rigctl").
As the port / address enter the Pi's name or address and the port: ft991a.local:4532 or 192.168.1.50:4532. (Use the name shown in your browser's address bar. If .local names do not work on that computer, use the Pi's IP address.)
Save, then connect. The frequency and mode in Log4OM should now follow the radio; clicking a spot should retune it.

The wording of the Log4OM menus changes between versions. What matters: Hamlib, model NET rigctl, address host:4532. Other logbooks use the same three settings, sometimes under the name "rigctld" or "Hamlib NET rigctl".

From the command line (to check it)

With Hamlib installed on any computer:

rigctl -m 2 -r ft991a.local:4532 f        # prints the frequency
rigctl -m 2 -r ft991a.local:4532 m        # mode and passband
rigctl -m 2 -r ft991a.local:4532 F 7074000

If it does not work

Symptom	Likely cause
The card says "Switched off"	tick the box and press Apply
The logbook cannot connect	wrong name/address, a firewall on the Pi, or the logbook's computer is outside the allowed addresses (the card counts "refused" connections, and the log says `rigctl: refused`)
It connects but the frequency never changes	the radio is off or disconnected (the link answers "I/O error" then); check the radio tab shows a green dot
Setting a frequency does nothing	"Let the logbook change frequency and mode" is off, the radio is transmitting, or the frequency is outside the radio's range
Mode shows wrongly	Hamlib has fewer mode names than the radio: DATA-U shows as PKTUSB, DATA-L as PKTLSB, narrow FM/AM as FM/AM

Every frequency or mode change made through the link is written to the audit log (Admin > Audit) with the computer's address.