Beckhoff EL34 Series, Documentation

Page: 86 / 295

Commissioning
EL34xx 86 Version: 1.5
Fig. 77: Selecting several PDOs simultaneously: activate "Continuous" and "All types"
Note that the "Continuous" checkbox was also activated. This is designed to allocate the bits contained in the
byte of the variable "nEL2008_value" sequentially to all eight selected output bits of the EL2008 terminal. In
this way it is possible to subsequently address all eight outputs of the terminal in the program with a byte
corresponding to bit 0 for channel 1 to bit 7 for channel 8 of the PLC. A special symbol ( ) at the yellow or
red object of the variable indicates that a link exists. The links can also be checked by selecting a "Goto Link
Variable” from the context menu of a variable. The object opposite, in this case the PDO, is automatically
selected:
Fig. 78: Application of a "Goto Link" variable, using "MAIN.bEL1004_Ch4" as a sample
The process of creating links can also take place in the opposite direction, i.e. starting with individual PDOs
to variable. However, in this example it would then not be possible to select all output bits for the EL2008,
since the terminal only makes individual digital outputs available. If a terminal has a byte, word, integer or
similar PDO, it is possible to allocate this a set of bit-standardised variables (type "BOOL"). Here, too, a
"Goto Link Variable” from the context menu of a PDO can be executed in the other direction, so that the
respective PLC instance can then be selected.