Greetings gdshd ...
the response from my distinguished colleague Ken Moore is correct – but it still might not answer your question ...
before we go any further, here’s a question for you ... why do you want to know? ...
if it’s so that you can CHANGE the time base “on the fly” by having your ladder logic program toggle a bit in your program – then I doubt that you’re going to be successful in that enterprise ... the “time base” bit located in the timer’s “memory area” is more or less “read only” ... specifically, changing the status of the bit will NOT change the operation of the timer in any way ...
more specifically, if you’re trying to do what I THINK you’re trying to do, then you’re probably going to need to manually “edit” the TON instruction ...
going further ... if you try to control the bit T4:0/9 by using something like a simple OTE instruction, then you’ll probably get a notice like “Can’t access control word bits!” in the “Status Line” (lower left corner of RSLogix500 window) ... in other words, RSLogix500 won't normally allow you to go into that area of the timer’s memory ...
going ever further ... if you really and truly have your heart set on accessing that bit, we CAN tell you how to do it ... even so, whenever I toggle that bit on and off here in the lab, the timer’s operation does NOT change – and the “Time Base” displayed in the TON instruction does NOT change either ...
sorry if this sounds like it’s going in circles ... give us more information about what you’re trying to do and we’ll straighten it all out ...
and welcome to the forum ...