Rs 232 Relay Control Board using PIC16F84A




Project Summary

Computer Controlled, relay board designed to be either operated manually via switches on the board or nine way Type Connector via PC or laptop. Provision has been made for USB serial adaptor. The Project utilises PIC Micro technology with windows visual interface written C Sharp utilising Dot Net version 4. It can be interfaced to other adapters Keypad adapter (Optional) or RF receiver (Optional) or Via the Net (Optional) Can be adapted to operate other external attachments such as Automatic Security Gates, Slave Flash or multiple Strobe lights for both professional or amateur photographers

Relay board

Project Description

Can be interfaced to other adapters Keypad adapter (Optional) or RF receiver (Optional) or Via the Net (Optional)
Can be adapted to operate other external attachments such as Automatic Security Gates, Slave Flash or multiple Strobe lights for both professional or amateur photographers

Main Features

Single pole Double throw relays contact rated at 10 amps 14 volts DC
Led Indication for each relay advising Off or On status
Independent manual switching for each relay
Full isolation between relays and CPU via Opto Couplers to eliminate noise, possible destruction of CPU
On Board mains Supply or alternative DC Jack for independent 12 – 14 volts Dc Supply
Mode switch controls manual or Pc control
Mode led advises user of what mode , state of the Board has entered
Can be interfaced to other adapters Keypad adapter (Optional) or RF receiver (Optional) or Via the Net (Optional)
Can be adapted to operate other external attachments such as Automatic Security Gates , Slave Flash or multiple Strobe lights for both professional or amateur photographers

The circuit comprises
A Level converter for conversion of Rs232 signals to TTL level this being U1 Max232

Five input switches , Four of which control the relays for manual operation , One of which is used to detect or switch the state of the Relay PCB to Serial control via the PC or Rs232 cable

A central cpu processing unit which performs the switch detection and subsequent relay triggering , more importantly determines the Rs232 signal input and extracts the commands sent to the board thus operating the relays individually or as a group

In other words the board has the ability to switch all four relays , 3 relays combination of in one single operation This is controlled via the Visual CSharp Interface

Four switching transistors to drive the relays with LED indication for each relay

Four Opto-couplers which in turn drive the relevant relay driver transistors isolating the CPU from the driver transistors This not only prevents possible damage to the CPU but also improves transient electrical noise which can, and does upset the PIC Micro registers due to the induced emf from the Relay coils

Two other led’s which indicate power to the Board , Mode selection in the following order

Schematic Relay board




1: Manual operation
2: Automatic operation in other words serial receive
3: One wire bus to be implemented

Points one and two are again controlled via the Visual interface

Provision has also been made for either USB to serial conversion using FTDI chips .

 

For more detail: Rs 232 Relay Control Board using PIC16F84A




Current Project / Post can also be found using:

  • 16f84a project with relays
  • diy serial relay controller
  • relay control
  • relay rs232 circuit

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