faster plc's?

[hyperdyne]

i am currently doing a project using dvt vision and a plc for sorting. the problem is that the AB micrologix that i am for the sorting routine is not keeping up with the machine. i am using a fifo buffer and have about 12 lines of programming for the machine. the software says it is running at 5-10ms scan time...but the scan time only shows up in 5ms increments.

i need a faster plc, anyone got any suggestions?

[support]

How fast do you need to sense the parts. is a FIFO buffer a bit shifter? That can be done quite quickly with the SHIFT command in the M-series PLC.  You can also use the interrupt capability of the PLC to sense the parts and execute the sort routine independent of the ladder logic scan time.

[hyperdyne]

we have 3 possibilities, so i am using an integer type fifo register. using a bit register might be possible with multiple registers.

speed wise, we are sorting 1000 pieces a minute.

[support]

Bit shifting is very fast and you can shift as many adjacent registers as you like. E.g. you can contruct a 64 bit left shift of relay registers:

   LSHIFT RELAY[1], 4

you can also implement an integer fifo buffer using the DM[n] where n is an index.

  DM[N] = ....
  N = N + 1
  IF N > 10  
        N = 1       'implements a 10 position buffer.
  ENDIF  

For 1000 pieces a minutes it means about 16 pieces a second. It shouldn't to pose a problem for our PLC.