Serial Back to Back Controllers
SKU: KTA-239

Description:

We have now reprogrammed our KTA-235 Remote Telemetry Unit or RTU to operate as a back to back controller.

What is a Back to Back Controller?
The KTA-238 has 4 isolated digital inputs, 2 non isolated 0-5V digital inputs and 6 relay outputs. Two KTA-238's are connected by a communications link. The link can be RS232, RS485 or wireless. The status of the inputs for each controller are automatically transmitted to the other controller where they are written to the relay outputs.

How does it work?
When an input on a controller changes the controller sends a command #RXX to the other controller. The value XX is a binary copy of its inputs. For example 07 means inputs 1,2 and 3 are on and input 4 is off. The receiving controller copies the XX value to relays. Thus the value 07 means relays 1,2 and 3 are on and relay 4 is off. The receiving controller then reads its inputs and transmits back #IYY where YY is a binary copy of its inputs Also each controller calculates a random time interval. When the interval has elapsed it sends the #RXX command to the other controller.

In the diagram below you will see the switch S1 at Site 2 turns on Motor 1 at Site 1 the switch S2 at Site 2 turns on Lamp 2 at Site 1 the switch S3 at Site 2 turns on Horn 3 at Site 1 the switch S5 at Site 1 turns on Lamp 5 at Site 2

 

Communications Link
The controllers come in 2 forms The KTA-238 is fitted with our 433MHz 1200 Baud LPID Wireless modules and antenna (see picture above). The KTA-239 communicates over RS232 which can communicate up to a distance of 100m at 1200 baud Make a D9 Cable to D9 Male cable. Pin 2 to Pin 3, Pin 3 to Pin 2 and Pin 5 to Pin 5. Use our IC-150 Non-Powered RS-232 Line Drivers to extend the distance to 1000meters using a 4 wire cable. Plug a line Driver into each of the controllers serial port. Use our RS232 to RS485 converters to extend the distance to over 1000 meters with a 2 wire connection. If you want a wireless connection use our low cost 9600 baud 433MHz Wireless modems.

As you can imagine the applications are endless Turn on a pump from your house. Security if a perimeter contact is broken a horn or lamp is activated at the central location. Alarm if a level in a tank gets low or high an alarm is activated.

Each KTA-238 controller provides 6 changeover relay outputs each capable of switching 5 amps @240VAC and four opto-isolated digital inputs. All connections to the I/O are via screw connectors.

Measures 135(L) x 140(W) x 35(H)mm

Download datasheet

Shipping Weight: 0.50 kg