Introduction

The present function blocks simplify data exchange between the TwinCAT PLC runtime system and/or other ADS devices (TwinCAT NC, Bus Terminal Controller, ...).

The FB_WriteXXXOnDelta() function blocks implement a write procedure when the input signal rises above or falls below a specified limit value. The frequency with which the input signal is examined can be set. Event-driven data writing minimises the loading on the fieldbus. If an error occurs during transmission, the process is repeated until the connection is established once more. All data types supported in the TwinCAT PLC are permitted as source and destination variables. Symbol names are also supported.

The FB_XXXAdsSymByName() function blocks execute a procedure to write or read the name of the PLC variable.

Watchdog blocks are available to monitor individual communication partners. The device that is to be monitored cyclically transmits an incrementing counter. A check is made at the receiver to see that the counter state changes within a specific time.