Need some advice or pointers for this sequencer

[Plastic]

sequencer - there may be a better way

I am programming a sequencer to turn on turn the outputs on and off in the following manner. Only one output will be on at a time. 0→1→2→3→7→11→10→9→8→4 then repeat the sequence. I have this correct so far.

But I also want to turn on output 5 during the first cycle and all odd numbered passes and have 6 on during the second cycle and all even passes with it. This is the part I am having trouble with.

I tried adding in a counter to look at the odd and even counts but could not quit figure out how to do it, Some advice and tips would be great.

I can't seem to figure out how to attach what I have done so I will try explain it.

Rung000- NO Start I:1/0, NC t4:0/DN, TON Timer to turn on each output light every .5 seconds.

Rung 001- NO T4:0/DN, SQO with File: N7:0
Mask:FFFFh
Dest: 0:2
Control: R6:0
Length: 10
Postion:0

I hope you can visualize what I have. That part works but I cant seem to figure out how to tackle the part that I listed above.

Sequencers

Using sequencers in Industrial PLC.

There is only one determination to consider before using a PLC sequencer instruction. If the application is 100% PLC outputs only, and 000.00% PLC inputs, then YES use a sequencer instruction. This sequencer can increment on blind time pulses, or blind event input. The result of the sequencer will to attempt to energize outputs in a rigid, deterministic pattern.

Two perfect examples of this application are: Christmas lighting, or Bellagio style fountain spout control. This sequencer will turn on, and turn off PLC outputs faithfully.

Your described application was: “We want the outputs to do exactly this, but every other cycle we want to alternate one output”. Well, that is easy, just write the sequence two full iterations deep, and include the alternating output in the overall sequence.

If your application has various input scenarios from either user inputs, or PLC real environment inputs, then, NO, DO NOT use a sequencer. Please use simple Boolean branch programming for each individual output, to respond to the alternate environmental situations.

Food for thought. We have programmed 100+ machines/assembly automation cells over the last 30 years, and never used a “sequencer”. Also note: We were victimized trying to understand, and modify an inflexible sequencer implemented by a firm that did not understand that the manufacturing work-flow is under constant scrutiny, and modification for optimization.

Also noted, we are not condemning programming techniques that are not readily understood, I am cautioning against programming techniques that are inflexible for the reality that manufacturing environment WILL change.