Save counter value

The latch function enables the current counter value to be stored in separate process data, independent of the cycle time. The Gate/Latch input can be parameterized as a second external latch input with separate process data. The latch function can be triggered as follows:

Latch input: positive/negative edge at the Latch input (Enable latch extern on positive/negative edge)
Gate/Latch input: positive/negative edge at the Gate/Latch input (Enable latch extern 2 on positive/negative edge)
Zero pulse C input: via the zero pulse C (Enable latch C)

Index 0x80n0:22 "Enable continuous latch extern" and 0x80n0:23 "Enable continuous latch extern 2" can be used to parameterize whether the function is executed at every parameterized external edge at the Latch input or only once after every activation.

A workpiece measurement can be realized by using two independent Latch inputs.

	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.

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 0x70n0:02 "Enable latch extern on positive edge" = TRUE
At the first external latch pulse with positive edge the current counter value is stored in index 0x60n0:12 "Latch value".
Index 0x70n0:04 "Enable latch extern on negative edge" = TRUE
At the first external latch pulse with negative edge the current counter value is stored in index 0x60n0:12 "Latch value".
Simultaneous activation of 0x70n0:02 and 0x70n0:04
The current counter value is stored in index 0x60n0:12 "Latch value", at the first external latch pulse, independent of the edge polarity.

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

"Enable continuous latch extern" Index 0x80n0:22 = FALSE
The following pulses at the Latch extern input have no influence on the latch value in index 0x60n0:12 "Latch value" when the bit in index 0x70n0:02 or 0x70n0:04 is set.
A new counter value can only be written to the Latch input in index 0x60n0:12 "Latch value" if index 0x60n0:02 "Latch extern valid" is FALSE
"Enable continuous latch extern" Index 0x80n0:22 = TRUE
The counter value is written to index 0x60n0:12 "Latch value" at every parameterized edge at the Latch extern input.
There is no need to reactivate index 0x70n0:02 or 0x70n0:04.

Saving of the counter value in index 0x60n0:12 "Latch value" is confirmed via the "Latch extern valid" bit (index 0x60n0:02).
The status of the Latch extern input can be monitored via index 0x60n2:14 "Status of extern latch".

	Simultaneous activation of "Enable continuous latch extern" and "Enable latch C" When using 0x70n0:02/0x70n0:04 "Enable latch extern on positive/negative edge", by activating 0x80n0:22 "Enable continuous latch extern" simultaneously with 0x70n0:01 "Enable latch C" Only the first event, either pos./neg. edge at the Latch extern input or the zero pulse C, is written to index 0x60n0:12 "Latch value". Saving of the counter value is confirmed by index 0x60n0:02 "Latch extern valid" or index 0x60n01 "Latch C valid". All further edges at the Latch extern input are ignored. The counter value storage cannot be reactivated until all activated commands for latching the value have been deactivated.

Save counter value via a positive/negative edge at the Gate/Latch input (Enable latch extern 2 on positive/negative edge)

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.

The counter value at the Latch extern 2 input can be saved via:

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.

Save counter value via the zero pulse C input (Enable latch C)

The counter value can be stored at runtime via the process data and the zero pulse in "Latch value" (index 0x60n0:12).

The function is activated by setting the bit in "Enable latch C" (index 0x70n0:01) to TRUE.
The current counter value is saved in "Latch value" (Index 0x60n0:12) with the next zero pulse at input C. The subsequent pulses have no influence on the latch value.
The "Latch C valid" bit (Index 0x60n0:01) is set to TRUE.
After reactivating "Enable Latch C" (index 0x70n0:01) a new counter value cannot be written to the Latch input until the values of the "Enable Latch C" bit (index 0x70n0:01) and the "Latch C valid" bit (index 0x60n0:01) are FALSE.

Workpiece measurement

The two latch functions (Latch extern and Latch extern 2) can be used to measure workpieces or distances between two workpieces. To use the Latch extern 2 function, the gate should be deactivated via index 0x80n0:04 "Gate polarity" ("Disable gate" = 0).

Depending on the activation of the indices, the counter value may be stored via a rising or falling edge.

	"Continuous latch" for workpiece measurement To prevent the stored value from being overwritten, it is advisable to set the setting in index 0x80n0:22 "Enable continuous latch extern" to FALSE for the workpiece measurement.

Workpiece measurement sequence (example)

Index 0x70n0:02 "Enable latch extern on positive edge" = TRUE:
The current counter value is stored in index 0x60n0:12 "Latch value" at the first pulse with positive edge at the Latch extern input.
Saving of the counter value in index 0x60n0:12 "Latch value" is confirmed via bit 0x60n0:02 "Latch extern valid".
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.
Saving of the counter value in index 0x60n0:22 "Latch value 2" is confirmed via the "Latch extern 2 valid" bit in index 0x60n2:12.
The end of the measurement is confirmed via the two activated bits in index 0x60n0:02 "Latch extern valid" and index 0x60n2:12 "Latch extern 2 valid".
The workpiece length can be calculated from the difference between the two values "Latch value" and "Latch value 2".
A new workpiece measurement can be started after the bits in index 0x70n0:02 "Enable latch extern on positive edge" and 0x70n0:0D "Enable latch extern 2 on negative edge" have been deactivated.