The SRC-4 Serial GPIO interface from Broadcast Tools ( ) is I/O device that features four optically isolated GPI/trigger inputs and four SPDT relay outputs to a RS-232 serial port.



The Broadcast Tools SRC-4 device is not developed or supported by Broadcast Radio, and this information is provided purely for reference purposes. The information contained in this article may be untested so you should ensure that the behaviour matches your requirements.


You will need to have installed the latest Hardware Service (at least v5.11 or higher) and also purchased a SRC-4 switcher. 

Attached to this article is a file called Broadcast Tools SRC-4.hwp. This file is a Hardware Preset that contains much of the required configuration already configured.

Virtual Network Device Configuration

After installing the HW Service and the SRC-4 unit as per the manual, go into the Hardware Configuration Tool and click Configure. Then right click on the Virtual Network Devices tree node and click Add Virtual Network Device


Click on Load Preset... in the top right hand corner and load in the Broadcast Tools SRC-4.hwp file that is attached to this article. This will preconfigure many of the settings for you.

Once the preset has loaded, change the Device Description to "Broadcast Tools SRC-4", and ensure that the the Use COM port: checkbox is checked, and that you select the COM port that the SRC-4 device is connected to. In our example, we are using COM3.



This configuration works in the following ways:

Command Terminator is set to "%0A" so that each line message will have that appended to the string being sent, and the incoming strings are checked for that character. 

Lines 1 to 4:

The first 4 lines are the "input" lines and will be activated and de-activated as opto-isolated inputs change.

Lines 5 to 12:

There are 2 lines allocated to each of the relay outputs - a Pulse and a Latch.

Activating Line 5 will "pulse" relay output 1 on for a brief moment, then the SRC-4 automatically turns it off. Normally you would use this with a "Pulse" instruction from whatever is connected to the Hardware Service so that the Hardware Service also automatically turns the line back off again after 1 second.

Activating Line 6 will turn on relay output 1, and it will remain on until you turn line 6 back off again, at which point it will turn off relay output 1.

This pattern repeats for all 4 available relays.