Home :: Controllers :: PC Based :: Relayduino USB/RS-485 IO Module 8-28 VDC

Relayduino USB/RS-485 IO Module 8-28 VDC

Relayduino USB/RS-485 IO Module 8-28 VDC

KTA-223 can now be powered 8-28VDC, therefore KTB-223 has been discountinued.

The KTA-223 is a USB or RS-485 controlled IO module for interfacing PCs to real world applications, such as controlling lights and sprinkler systems, reading sensors and monitoring switches and other digital signals. It's also an Arduino compatible controller and can be programmed with Arduino IDE for stand-alone operation.

The relays are capable of switching up to 10 A at 250 VAC (though see notes about PCB track heating in the manual). Optically-isolated digital inputs can be wired to NPN, PNP or dry contact (switch) type sensors. Three analog inputs can be used for 0 to 5 VDC or 0 to 20 mA (including industry standard 4 to 20 mA) signals.

A simple ASCII protocol allows control from Windows/Mac/Linux using either USB Virtual serial port drivers or RS-485. Additionally, multiple devices can be connected to one RS-485 bus, allowing control of many devices from one USB port.

Multiple controllers can be connected to one or more PCs in an RS-485 network. Each controller can be assigned an address and will respond to commands addressed to them.

The controller is based on the hardware of the Arduino physical computing controllers. It can be programmed as a stand-alone controller using the free, open source Arduino environment. Internally, the controller is "shield compatible", allowing the use of many extension boards designed for the Arduino Deumilanove or Uno.


  • 8 relay outputs 10 A, 250 VAC
  • 4 Opto-isolated inputs 5 to 30 VDC
  • 3 Analog inputs (10 bit), jumper selectable for 0 to 5 VDC or 0 to 20 mA
  • Connections via pluggable screw terminals
  • Power Indicator, TX and RX LEDs
  • All enclosed in professional looking plastic case
  • Arduino compatible
  • Accepts Arduino shields (Ethernet / XBee)
  • Communicates via USB (virtual serial port) or RS-485
  • Easily connect multiple units far apart by RS-485
  • Dimensions (L × W × H): 14 × 11 × 3 cm
  • 8-28V DC powered; 500mA
  • -20°C to 70°C operating temperature

An example program has been written in both Visual Basic 6 and VB .Net to show you how to interface with the KTA-223 using a PC.

Light Flasher Software:

Our Light Flasher software for the KTA-223 called Time-A-Relay allows you to sequence the relays in patterns.This is designed for Christmas lights, trapshooting and other simple time loop controls.

Time Clock Software:

Our Time Clock software for the KTA-223 called Time-Clock allows you to switch on relays at certain times of the day and days of the week. Can be used to control lighting and watering for plants etc.

Web Interface Sketch:

Using the WebUi sketch and an Ethernet shield allows you to control the IO from a web browser

WiFly Interface Sketch:

Check out this item news for a tutorial on using the WiFly shield to control the IO from a web browser

The KTA-223 is also available cheaper as a kit and in a 24 VDC version.



SKU:  KTA-223

Qty. Price
(AUD ex. GST)
1 to 4 $149.00
5 to 9 $134.10 (10% off)
10+ $126.65 (15% off)