Repeater Controller Interfacing

From RLC Controllers - Support

Jump to: navigation, search


Computer Inteface for Programming

See Programming Using a Computer and Serial Port Interfacing.

General Radio Interfacing

Applies to all types of radios


The COR signal is an indication of whether a receiver's squelch is open or not. It is either on or off, not an indication of how good the signal is (like RSSI). COR stands for "Carrier Operated Relay" (though it isn't usually a relay in modern radios) and is also commonly known as COS (Carrier Operated Squelch) or CAS (Carrier Activated Squelch).

Virtually all repeater radios and most mobiles have a COR output that can be connected directly to an RLC controller's COR input. Most HT/portable radios do not, at least not one that is accessible without opening the radio and finding the right point inside. They are of limited use anyway, as they don't generally have enough output power or receiver filtering to work well at most radio sites. If you want to use a radio that doesn't have a COR output, see COR Alternatives.

Try just connecting the COR output from your receiver to the COR input of the controller, which is pin 7 of the DB-9 radio port connector (you will also need a common ground connection). If the controller has a COR LED, it should turn on/off when you open/close the squelch (don't worry yet about whether the LED is on when the squech is open or closed - we will deal with the in the COR polarity section below - just that it changes when you open and close the squelch). If the LED does not change, or your controller does not have an LED display for the COR signal, check the voltage with the squelch open and closed. With the radio and controller powered up, opening/closing the squelch should cause the COR voltage to change from below 0.5V to at least 3.5V. If the voltage does not change like that, see COR Buffer Circuits and Troubleshooting_COR_and_PL_signals.

COR Polarity

The LED should turn on when the squelch is open and off when the squelch is closed. If the LED turns on and off but works "backwards" (is on when the squelch is closed), the controller can usually be reconfigured to reverse the logic internally:

  • RLC-1: Use jumpers to change COR polarity (PL is always active low, use a buffer circuit to invert if necessary)
  • RLC-1 Plus or RLC-2: Use command 024
  • RLC-3: Use DIP switch #2 to change COR polarity, switch #3 to change PL polarity
  • RLC-4, RLC-5 or RLC-Club: Use command 013


  • Document what the LEDs indicate
  • Note which versions accept commands with either polarity and how to get rid of the delay before execute commands

PL(tm)/CTCSS Input

The controller has a PL detected input (sometimes called just a "PL input") that can be connected to a PL decoder, either one built into your receiver or an external one (Communications Specialists TS-32, now discontinued, and TS-64DS are common (include link)). Note that the RLC controllers do not have a PL decoder built in; the PL input is meant to be connected to an external decoder that provides a high/low voltage to indicate when it detects the PL tone. The controller's PL input hardware is identical to its COR input, so the information above about interfacing to a COR signal applies to the PL as well. It is very uncommon to need a buffer circuit for a PL detect signal.

Audio from the RX to the Controller

[Notes about impedances, audio level from receiver]

Audio from the Controller to the TX

[Notes about impedances, voltage dividers (which TX need them), disable internal loopback in radio]

Radio Control Data

The RLC repeater controllers can send two types of "serial" data. The most common type is exactly the same as a modem or serial mouse uses to communicate with a computer. It is sometimes called RS-232, SCI, or asynchronous serial data. It is sent with a specified baud rate that must be set the same on the sending and receiving end. It can be sent with two different voltage levels: RS-232 or TTL. The timing is exactly the same either way. RS-232 switches between positive and negative voltages of around 3 to 12V. TTL uses 0V and 5V. The TTL signal levels are usually used only for short internal connections, such as between a microprocessor and a chip that converts the signals to the RS-232 voltage levels, such as a DS-275 or Max232.

The other type of "serial" data is sometimes called SPI and is synchronous (rather than using a specified baud rate that must be set the same on both end, one end generates a clock signal that is sent on a separate wire from the data signal). It is used to communicate with some remote base interfaces (such as the RBI-1 and RLC-ICM), external shift registers (such as are used for the "extended output line" feature) and internally on the RLC-3 between the motherboard and radio cards. Most of the RLC controllers generate SPI serial data using the logic output lines, rather than a dedicated serial port (see RLC-3 Serial Interfaces for more info about it).

Also see Remote Bases.

Specific Radio Interfacing

See Remote Bases. has information about interfacing to the Yaesu VXR-5000 and VXR-7000 repeaters. has a lot of general information about modifying and interfacing to various brands of radios.

VoIP Interfaces

One of the Appendices in the manual has a lot of info about this.

Through a Radio

Direct Connection


[put this on another page?]

Logic Outputs

"Extended" Output Lines

Logic Inputs

Analog Inputs

Weather Stations

see Weather Stations

Personal tools