Bit
The Heidenhain bit trigger initiates data transfer when the assigned logical data point assumes the value 1. If the assigned data point is not a logical data point, the trigger is initiated when the data point assumes a value other than zero. You can also send a response and, in the event of a faulty transfer, an error message to two additional data points.
The individual properties are:
| Property | Description |
|---|---|
| Connection | Heidenhain connection via which the relevant data point is reached. |
| Data point | Data point that triggers the transfer as soon as it assumes a value other than 0. Use the "..." button to open the tag browser (see below) for interactive selection of an item. |
| Reset bit | Sets the data point to "0" after the transfer. Should normally be deactivated because a bit should only be written to from one side. Instead, use the response bit to inform the controller that the transfer has been completed. |
| Response bit active | Sends a bit to another data point as a response that the transfer has been completed. |
| Data point | Data point to which the response is sent. It must be a logical (bit) data point with a status of "0" or "1." Use the "..." button to open the tag browser (see below) for interactive selection of an item. |
| Reset response bit after | The response bit is reset after the set time period. |
| Error bit active | Sends a bit to another data point if the data transfer was faulty. |
| Data point | Data point to which the error bit is sent. It must be a logical (bit) data point with the status "0" or "1." Use the "..." button to open the tag browser (see below) for interactive selection of an item. |
| Wait for falling edge | If you do not want the OPC Router to trigger continuously when the bit is active, activate this checkbox. This causes the OPC Router to trigger only once when the bit is active and then wait for a "falling edge" before triggering again. |
Bit and message triggers for OPC telegrams
You use bit and message triggers for OPC telegrams if you want to read out several related items. The OPC Router waits for another read cycle before reading out the items in the OPC transfer object to ensure that the PLC was able to write all values. On the PLC side, the trigger should still be written at the end.
Bit triggers always with response bit
Always use the bit trigger with a response bit. If the data point in the PLC changes twice within a read cycle, the OPC Router does not notice this. The PLC must respond accordingly to the router's lack of response. Standard practice: A bit may only be written to by one side, i.e., the PLC resets the trigger data point after receiving the response. The OPC Router resets the response data point itself after a configurable period of time.