Input Description¶
SLOT
| Data_Type | Default_Value | Range | Unit |
|---|---|---|---|
| BYTE | - | - | - |
This input is used to select the slot (module number) of the DC541.
The slots are numbered consecutively from right to left. Slot 1 is the first slot on the left of the CPU.
CH (channel)
| Data_Type | Default_Value | Range | Unit |
|---|---|---|---|
| BYTE | - | 0-7 for the inputs C0-C7 | - |
CH is used to select the channel for time and frequency measurement. If an invalid value is specified at input CH or if the selected channel is not configured as frequency measurement, the function flock is aborted with DONE = ERR = TRUE and an error is displayed.
EN_VISU (enable \ input in visualization)
| Data_Type | Default_Value | Range | Unit |
|---|---|---|---|
| BOOL | - | - | - |
If this input is TRUE, it is possible to control the function block inputs (except SLOT, CH and EN_VISU) via the integrated visualization of the function block. If input EN_VISU = FALSE, control via the visualization is disabled and the labelling of the corresponding control elements is displayed in gray. The actual values are always displayed.
EN (enable)
| Data_Type | Default_Value | Range | Unit |
|---|---|---|---|
| BOOL | - | - | - |
In order to enable pulse counting for input CH, input EN has to be continuously TRUE. The Function Block is not processed if input EN = FALSE.
When the function block is called for the first time, the inputs are checked for validity and plausibility and the corresponding device is checked for correct configuration in the operating mode “counting mode”. If this is not the case, processing is aborted.
PREC (precision)
| Data_Type | Default_Value | Range | Unit |
|---|---|---|---|
| WORD | - | - | - |
Input is used to specify the demanded accuracy of the measurement.
PREC = 10 corresponds to an accuracy of 0.1 (one tenth)
PREC = 100 corresponds to an accuracy of 0.01 (one hundredth)
PREC = 1000 corresponds to an accuracy of 0.001 (one thousandth)
Depending on the cycle time and the demanded accuracy, the DC541 extends its measuring time and counts multiple pulses. This setting is only used in the frequency measurement operating mode (EN_FREQ = TRUE). Then, the displayed measurement values correspond to the measured average value. This reduces jitter and latency effects resulting in improved accuracy.
As the resolution for measuring is 1 µs, the precision corresponds directly to the measuring time in µs. For times < 100 µs, the device will just calculate the values as fast as possible, which will be the cycle time of the device, around 100 µs. For higher precision, the device will use the pulses per measuring time. It will measure the pulses and the time, with the time on a 1µs resolution.