Counter overflow and underflow

An overflow or underflow of the counter limits is indicated by the process data “Counter underflow” (0x60n0:04) or “Counter overflow” (0x60n0:05).

• The bit in the process data “Counter underflow” (0x60n0:04) is set when an underflow occurs 0x80n1:1B “Reset counter value” → 0x80n1:1A “Limit counter value”. With default parameters this corresponds to “..00 → ..FF”
  It is reset if 2/3 of the counting range are underrun.
• The bit in the process data “Counter overflow” (0x60n0:05) is set when an overflow occurs 0x80n1:1A “Limit counter value” → 0x80n1:1B “Reset counter value”. With default parameters “..FF → ..00”
  It is reset if 1/3 of the counter range is exceeded.