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8 Output Realy Board for PC Interface Hardware Project

For this board is designed specifically to control many motor for Robot Arm or motion system.
It has no input facilities, but it is less expensive than combining the I/O Board with the Relay sub-Board.
So I think , If you need lots of relays and no input, this is the way to go.

We has begin with the smaller items such as the 1N914 diodes and then the IC.
You can then start on the 'signal' items like LEDs, resistors, regulator, bridge, green cap, etc.
which once you have the basic components soldered in, carefully install the DB25 socket for connect to printer port.

you may be make sure that none of the pins get bent over as you're trying to wiggle everything into place.
It's a nightmare to unsolder the socket if you make a mistake! Leave the relays until last.
Any 12 -15 volt 1 amp minimum AC or DC power supply can be used.

Understanding in circuit diagram and process.

For output section is controlled by an eight line "Darlington Driver" integrated circuit (IC) or called a ULN2803 that using in thaiio's project. The digital state of each of the eight lines from the printer port is used to control the IC's internal "drivers" which in turn control the Relays and LEDs. Power for the relays and LEDs is provided using by the 12 volt regulator (LM 7812) via a plug pack power supply of at least 15 volts and capable of supplying at least 1 amp. In this interface, each of the eight output lines at the printer port is connected via a 560ohm to a LED. Four of the output lines also have relays attached.

   โครงงานนี้ เราจะนำไปใช้ได้ทั้งควบคุมอุปกรณ์ภายนอก เช่น สเต็ปมอเตอร์,เปิดปิดหลอดไฟ เป็นต้น
จริงแล้วพวกเราอาจจะรู้แล้วเพราะเป็นวงจรพื้นฐานทั่วไป ผมจะไม่ขอเอธิบายเป็นภาษาไทยมากนัก เพราะงไม่มีอะไรมาก ดูตามลำดับของเนื้อหาภาษาอังกฤษ แบบคราวๆก็คือ
  • ดูวงจรการต่อของ IC ULN2803 ซึ่งทำหน้าที่เป็น Driver ในการขับกระแสไฟฟ้าไปที่อุปกรณ์เช่น LED ,Relay
  • ทำ PCB ดังรูปด้านล่าง
  • จัดหาอุปกรณ์ ตามรายการด้านล่าง
  • จัดวางอุปกรณ์และทำการบัดกรี ดังรูปด้านล่าง
  • เขียนโปรแกรม ถ้าใครยังไม่รู้ก็ เข้ามาศึกษานี้ได้ครับ
    การเขียนโปรแกรมติดต่อ Printer Port

How to Coding for Control and Access Printer Port:

This code in control output thus below:

[Out : command][Address Port : ie. &378 ][Output Value : Hex]


[output code] = 1, 2, 4, 8, 16, 32, 64, or 128 and

[address port] if we use decemal may be 888, or 631 depending upon your hardware. if LPT 1 (888) doesn't work, try 631 which is LPT 2.


' This "4" is exemple value send to port.

C and C++ --| outp(0x378, 4);

Pascal ---|    Port[888] := 4;

BASIC ---|      OUT 888,4

Visual Basic 6 ---|
Click Here to Get the Dllport.dll I/O Parallel Port for Windows 95,98,NT,Me,Windown XP,2000

      Private Declare Sub Out Lib "DllPort.dll" Alias "Out32" (ByVal PortAddress As Integer, ByVal Value As Integer)
     Out(&H378, 4)

PCB Layout

8 relay board PCB

PCB Assemply

8 relay board PCB

Completed Assembly Board

Parts Component List

Item Description QTY
1 IC ULN 2803 8-way line driver 1
2 1N4004 Diode 1
3 LM7812 Voltage regulator (T220 case) 1
4 560 ohm 1/4 watt resistor 8
5 1N914 Diode 8
6 3mm Red LED 8
7 47uF Electrolytic Capacitor 1
7 0.01uF (approx) Green Cap 1
8 3mm red LEDs 8
9 SPDT 12 volt Relays 8
10 1 amp diode bridge 1
11 25 pin Serial Cable - Male to Male 1
12 12 - 24 volt power supply with 2.1mm Plug 1
13 PCB mounted DB 25 Socket 1
14 PCB 1

Final Recomment :

About once the value at the port has been read, you should be use "ANDing" to determine which individual line is either HIGH, or LOW.

The "PCB mounted DB25 Socket" connects via a 'serial' cable to the printer port.

Item 1: The cable must be a male-male (plug-plug) type with 'straight through' connections. ie 1 to 1, 2 to 2, 3 to 3, etc. This type of cable is commonly used with printer switch boxes. (A "null modem" cable has lines 2 and 3 crossed and is not suitable - unless you make allowances in your programming.)

Item 2: This power supply for the interface can be either AC or DC as long as it can deliver at least 1 amp. The diode bridge makes connection fool proof. The power supply can be connected either way around.

Referrent from : http://www.southwest.com.au/~jfuller/robotic.html

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