Friday 25 January 2013

Unserstanding Parallel Port Interfacing

Parallel Port Interfacing


A Parallel port is a type of socket which is use to interface various peripherals to your personal computer. It is commonly known as printer port.
PC Parallel port is 25 pin, D-shaped female connector in the back of computer. It is not necessary to every time you will use 25 pins, you can use 8 output pins (Data Lines) and single ground to achieve your task.

DB25 (Printer Port)

The DB25 (originally DE-25) connector is an analog 25-pin plug of D-subminiature connector family (D-Sub of Sub-D).
With the DB9 connector, the DB25 is mainly use for serial connections, allowing for the asynchronous transmission of data as provided by standard RS-232 (RS-232C).
it is also used for parallel port connections, and was originally used to connect printers, that is why it is known as "printer port" (LPT for short).
some time there is confusion so you should be very much clear that DB25 serial port in computer generally have male connectors, while parallel port connectors are DB25 female plugs.

Pins configuration (serial connection)

Pin number
Name
2
TXD - Transmit Data
3
RXD - Receive Data
4
RTS - Request To Send
5
CTS - Clear To Send
6
DSR - Data Set Ready
7
GND - Signal Ground
8
CD - Carrier Detect
20
DTR - Data Terminal Ready
22
RI - Ring Indicator

Pins configuration (parallel connection)

Pin number
Name
1
_STR - Strobe
2
D0 - Data bit 0
3
D1 - Data bit 1
4
D2 - Data bit 2
5
D3 - Data bit 3
6
D4 - Data bit 4
7
D5 - Data bit 5
8
D6 - Data bit 6
9
D7 - Data bit 7
10
ACK - Acknowledgement
11
Busy
12
Paper Out
13
Select
14
Auto feed
15
Error
16
Reset
17
Select Input
18
Ground
19
Ground
20
Ground
21
Ground
22
Ground
23
Ground
24
Ground
25
Ground

The Original IBM-PC's parallel port had a total of 12 digital outputs and 5 digital inputs accessed via 3 consecutive 8-bit ports in the processor's I/O space.

Pin out:

Pin description:

Because of security purpose you can not directly access parallel port in windows XP, vista etc. To access the port follow these steps.
  1. first go to the BIOS setting.
  2. then select advanced option.
  3. under this option select peripheral configuration
  4. then change the setting of parallel port as
    1. enable
    2. bi-directional
    3. IRQ-7

After doing these steps download the user port and follow the instructions. A window will open, when you will run userport.exe, asking the range.
To find this:
  1. right click on my computer icon
  2. select manage
  3. from device manager select ports(com &LPT)
  4. double click on printer port
  5. a window will open, choose the resources tab you will find



Fill this range in both the spaces and then click on add button. Then click on start button three times, a message will appear just click ok.
Now your port is ready for interfacing.

1 comment:

  1. That it minimum number of wires is necessary, to work male and female connector?

    ReplyDelete