Siemens SIMATIC S5 IP 281 Equipment Manual page 168

R 11192
STO Digital stop input
Synchronous control
Synchronous read
Underflow. Lower counting range limit has been passed below.
TCAR Transfer counting value to alarm register (i.e., interrupt register), a combination
operating mode
TCLR Transfer counting value of counter 1 to load register of counter 2, a combination
operating mode
ZMPC Zero marking pulse of encoder 1 to counter 2, a combination operating mode
AG 1992, Order No: 6ES5 998-0KP21
Definition of Terms
D – 3