Latch input (Latch extern)
The terminal provides a latch input (Latch extern) for 24 VDC signals with a minimum pulse duration of tON > 1 µs. This can be used as follows:
- Counter value reset:
the counter value is reset to the value set in index 0x8001:1B "Reset counter value" (default setting: "0") (Enable extern reset) - Set counter value:
set the counter value to a predefined counter value via a positive or negative edge (Set counter on latch extern on positive/negative edge) - Save counter value:
save the counter value in separate process data via a positive or negative edge (Enable latch extern on positive/negative edge)
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".