TwinCAT tree

The operating principle of the EL47xx in conjunction with SYNC0 and SYNC1 pulses was already described in section "Basic Function Principles". This section describes the application of the Beckhoff TwinCAT System Manager for setting the parameters.

Once the terminal has been scanned in, the following tree structure appears (see Fig. TwinCAT tree EL4732).

Ch1/Ch2 CycleCount and Ch1/Ch2 Value

Each EL4732 record contains a CycleCounter for each channel that is incremented with each record, and n analog measured values with a width of 2 bytes each. With an oversampling factor of n = 25 a record therefore consists of a 16-bit CycleCounter (overflowing) and 25 16-bit samples per channel. The CycleCounter in the higher-level control system can be used to verify the consistency of the record transfer.

By default the EL47xx is set to n = 1, resulting in the process image shown in Fig. TwinCAT tree EL4732.

WcState 0/1 (Online tab)

Boolean variable indicating the working counter status of the terminal. An invalid working counter (value: 1) is displayed if the EtherCAT slave with its EtherCAT slave controller (ESC) did not read or write process data from or to the EtherCAT frame read.

InfoData, State

Shows the online status (EtherCAT state machine) of the terminal.

Table 1: States of the EtherCAT state machine