could any one help me in writing one plc program

If you don't want to find out about shift instructions (which would be the most efficient way to do it), just use your pushbutton input to increment a counter from 1 to 5 (or 0 to 4), remembering to reset it on the next push after maximum count. Follow this with a series of EQU and NEQ ladder rungs to turn the outputs ON or OFF as required. You can save instructions here by using EQU and OTE (instead of OTL and OTU).

Remember to use an ONS instruction after the button-pressed test, so it is only 'seen' once per push.

mdhilal,

Another way is to treat the outputs as a word with an arithmetic value multiplied by two each time the input button is pressed, and reset to 1 when the value exceeds the maximum for the number of outputs used. You would have to initialize it of course. Be careful to note that zero (0) is not the letter O, nor one (1) the letter I.

Rung-0: XIC S:1/15 MOV 0 O:2

Rung-1: XIC I:1/1 OSR B3/1 BST MUL O:2 2 O:2 NXB EQU O:2 0 MOV 1 O:2 BND

Rung-2: GRT O:2 16 MOV 1 O:2

Comments: In rung-0, in the first pass when the processor goes to run, the outputs are all turned off. In rung-1, each time the input button is pressed, the value of O:2 (the outputs) is doubled, but if it is zero, it is set to one. (The doubling is the basic "shift register" function of the program; the setting it to one is to turn it on the first time the button is pressed. In rung-2, if the value of O:2 is greater than 16 (which would occur when O:2/5 tries to be turned on), it is reset to 1, which turns on O:2/0. If the input had a tendency for a contact to "bounce", you could use a timer to require a minimum elapsed time before a second input closure would be accepted. If you wanted the lights to all go off for one button pressing after the highest one, rung-2 would move 0 to O:2.

If you want the program to start with the first output on when the processor goes to run, then rung-0 and rung-1 need to be changed so the program reads as follows:

Rung-0 XIC S:1/15 MOV 1 O:2

Rung-1 XIC I:1/1 OSR B3/1 MUL O:2 2 O:2

Rung-2 GRT O:2 16 MOV 1 O:2

If you are unfamiliar with the mnemonic codes for entering the program, which I am using above, just get to the rung and try typing the code as I listed it. You will see a text window on the rung, and when you hit the ENTER key at the end of each line of code you will see the completed code in its more common "ladder" format.

This version of the program allows a very easy adjustment to the number of outputs being turned on/off. All you need to do is change the value in rung-2 from 16 to the proper multiple of 2 (using 2^(n-1)) for n<8 being the highest output being sequenced.

Have fun--JMM