Hello Dperez,
The SLC500 and PLC5 have both a minimum of 10 ms. You have adjust the base time in 0.01 s and 1 as base time count.
Beware that if you have a scan time greater than 10 ms you will not have an acurate timing, because the complete program have to run before you see the timer expiration. A posible fix to this is to use interrupts. SLC503 and higher have a STI instruction with a resolution of 1ms.
Micrologix series of PLC's have a minimum of 1ms, but the same considerations about scan time applies.
Best regards