Allen-Bradley Logix5000 Reference Manual page 126

Chapter 3 Timer and Counter Instructions (TON, TOF, RTO, TONR, TOFR, RTOR, CTU, CTD, CTUD, RES)
Arithmetic Status Flags:
Fault Conditions:
126
Not affected
A major fault will occur if
.PRE < 0
.ACC < 0
Rockwell Automation Publication 1756-RM003N-EN-P - October 2011
Fault type Fault code
4 34
4 34