TGIC got lucky in using AB nomencalture. But since Pratik is in the US, there was probably a 50-50 chance of being correct (marketshare being what it is).
I think ALL PLCs have a done bit. It may not be called .DN (most likely not, in fact), but there will be some mechanism of setting a bit when the timer times out.
The AB .EN bit is somewhat unusual, but not that hard to duplicate. Essentially, it's the conditions that make the Timer true. A branch around the timer with a coil would work the same. In the case of the example, the done bit of the previous timer is the logical equivalent of the enable bit.
The .TT bit (for Timer Timing) is a strange beast, however. The logic for it is "Enabled, but not Done". Or
EN DN TT
---| |---|/|------( )
Since, in the example, the previous timer's done bit is the enable bit, and since the second timer's done bit resets the first timer, you could just use the first timer's done bit to drive the output if you like.
AB Style
T4:1/DN +---- TON ---+
----|/|--------|Timer T4:0 |
| 8 hours |
+------------+
T4:0/DN +---- TON ---+
----|0|--------|Timer T4:1 |
| 10 min |
+------------+
T4:1/TT WIPER
----| |-----------------( )
Generic PLC Style
TIMER1 TIMER0
-----|/|-----[TON ]
[ 8 Hr]
TIMER0 TIMER1
-----| |-----[TON ]
[10 MIN]
TIMER0 WIPER
-----| |-------( )
The explanation, without ladder, in 25 words or less:
Use two timers. The timeout of the first starts the second. The timeout of the second resets both. When the first timer times out, drive your output.
(OK, so that's 27 words.)
