Latch input (Latch extern)

The terminal provides a latch input (Latch extern) for 24 V_DC signals with a minimum pulse duration of t_ON > 1 µs. This can be used as follows:

Counter value reset via the Latch extern input (Enable extern reset)

The counter value can be set to "0" via the Latch extern input.

• Presetting of the reset value via index 0x8001:1B "Reset counter value", (Default: 0)
• To activate this function set the bit in index 0x8000:02 "Enable extern reset".
• Index 0x8000:10 "Extern reset polarity" can be used to specify at which edge the Latch extern input is active.
• 0: "Fall" - the counter is set to "0" with a falling edge
• 1: "Rise" - the counter is set to "0" with a rising edge

There is no status message via the process data.

Set counter via the Latch extern input (Set counter on latch extern on positive/negative edge)

The counter value can be set to a preset value during runtime via the process data by the positive or negative edge at the Latch extern input.

• Counter value setting via index 0x70n0:11 "Set counter value"
• Activation of the counter value setting via
• the positive edge at the Latch extern input:
  index 0x70n0:0A "Set counter on latch extern on positive edge"
• the negative edge at the Latch extern input:
  index 0x70n0:0B "Set counter on latch extern on negative edge"
• If the bit is set (TRUE) in index 0x70n0:0A or 0x070n0:0B, the counter value is set to the specified value at the next rising or falling edge at the Latch extern input.
• For confirmation the "Set counter done" bit (index 0x60n0:03) is set to TRUE.
• The counter value specification cannot be reactivated until index 0x70n0:0A/0B "Set counter on latch extern on positive/negative edge" is set to FALSE.

Save counter value via a positive/negative edge at the Latch input (Enable latch extern on positive/negative edge)

• The counter value at the Latch extern input can be saved via:
• Index 0x7000:02 "Enable latch extern on positive edge" = TRUE
  At the first external latch pulse with positive edge the current counter value is stored in index 0x6000:12 "Latch value".
• Index 0x7000:04 "Enable latch extern on negative edge" = TRUE
  At the first external latch pulse with negative edge the current counter value is stored in index 0x6000:12 "Latch value".
• Simultaneous activation of 0x7000:02 and 0x7000:04
  On the first external Latch pulse, regardless of the polarity of the edge, the current counter value is stored in index 0x6000:12 "Latch value".
• Specification whether it is necessary to reactivate the command to save the counter value via:
• "Enable continuous latch extern" index 0x8000:22 = FALSE
  The following pulses at the latch extern input have no influence on the latch value in index 0x6000:12 "Latch value" if the bit in index 0x7000:02 or 0x7000:04 is set.
  Only when index 0x6000:02 "Latch extern valid" is FALSE, a new counter value can be written to the latch input in index 0x60n0:12 "Latch value"
• "Enable continuous latch extern" index 0x8000:22 = TRUE
  The counter value is written to index 0x60n00:12 "Latch value" with each parameterized edge at the latch extern input.
  A new activation of index 0x7000:02 or 0x7000:04 is omitted.
• Saving of the counter value in index 0x6000:12 "Latch value" is confirmed via the "Latch extern valid" bit (index 0x6000:02).
• The status of the Latch extern input can be monitored via index 0x6002:14 "Status of extern latch".