Gate/Latch input

The terminal provides an external Gate/Latch input for 24 V_DC signals with a minimum pulse duration of t_ON > 1 µs. This can be used as follows:

Lock counter value:
lock the counter value via a positive or negative edge (Enable pos/neg. gate)
Save counter value:
save the counter value in separate process data via a positive or negative edge (Enable latch extern 2 on positive/negative edge)

Lock counter value via a positive/negative edge at the gate input (Enable pos./neg. gate)

The level at the Gate input at which the counter value is locked during runtime can be specified via index 0x80n0:04 "Gate polarity".

0: Disable gate
The Gate/Latch input is disabled. It can still be used as Latch extern 2 input.
1: Enable pos. gate
The counter value is locked with HIGH level at the Gate/Latch input.
2: Enable neg. gate
The counter value is locked with LOW level at the Gate/Latch input.

The current level at the Gate input is displayed via process data 0x60n0:0C "Status of input gate".

The terminal offers the option of using the Gate/Latch input as a second Latch input (Latch extern 2). To do this, the gate should be deactivated.

	Deactivation of the gate Set the "Gate polarity" bit (index 0x80n0:04) to "0 - Disable gate" in order to be able to use the Latch extern 2 input without disabling the counter value after the latch event.

Index 0x70n0:0C "Enable latch extern 2 on positive edge" = TRUE
The current counter value is stored in index 0x60n0:22 "Latch value 2" at the first external pulse with positive edge at the Gate/Latch input.
Index 0x70n0:0D "Enable latch extern 2 on negative edge" = TRUE
The current counter value is stored in index 0x60n0:22 "Latch value 2" at the first external pulse with negative edge at the Gate/Latch input.
Simultaneous activation of 0x70n0:0C and 0x70n0:0D
The current counter value is stored in index 0x60n0:22 "Latch value 2" at the first pulse at the Gate/Latch input, independent of the edge polarity.

Specification whether it is necessary to reactivate the command to save the counter value via:

"Enable continuous latch extern 2" Index 0x80n0:23 = FALSE
The following pulses at the Gate/Latch input have no influence on the latch value in index 0x60n0:22 "Latch value 2" when the bit in index 0x70n0:0C or 0x70n0:0D is set.
A new counter value can only be written to the Gate/Latch input in index 0x60n0:22 "Latch value 2" if index 0x60n2:12 "Latch extern 2 valid" is FALSE.
"Enable continuous latch extern 2" Index 0x80n0:23= TRUE
The counter value is written to index 0x60n2:12 "Latch value 2" at every parameterized edge at the Gate/Latch input.
There is no need to reactivate index 0x70n0:0C or 0x70n0:0D.

The status of the Gate/Latch input can be recorded via index 0x60n0:0C "Status of input gate".
Saving of the counter value in index 0x60n0:22 "Latch value 2" is confirmed via bit 0x60n2:12 "Latch extern 2 valid".

	Simultaneous use of Gate und Latch extern 2 When using index 0x80n0:04 "Gate polarity" (1 = "Enable pos. gate") and simultaneously activating index 0x70n0:0C "Enable latch extern 2 on positive edge", the current counter value is initially stored in index 0x60n0:22 "Latch value 2" when a positive edge is detected at the Gate/Latch input. The counter value is then blocked. The same applies to the use of index 0x80n0:04 "Gate polarity" (2 = "Enable neg. gate") and simultaneous activation of index 0x70n0:0D "Enable latch extern 2 on negative edge" at a negative edge at the Gate/Latch input.

	Multiple activation of the latch function If several commands are activated simultaneously to save the counter value in the "Latch value" process data (index 0x60n0:12), only the command that is set first is accepted by the terminal. The counter value is stored in the "Latch value" (index 0x60n0:12) at the next occurring event and confirmed with the corresponding bit. All other activated events are ignored. The counter value storage cannot be reactivated until all activated commands for latching the value have been deactivated. This also applies if they were activated after confirmation by the occurring event.