direct key handling FC57

Function block for connection between the OP012 direct keys and the Siemens

Transline data bar DB59.

PLEASE NOTE: As system requirements the version >=V3.0.20 of HMI PRO is 

obligatory!

For the version V3.1 of HMI PRO the FC includes a functional upgrade for 

monitoring

the connection between OP012 and PLC.

This monitoring is active as soon as a value for monitoring time is written 

from HMI 

into DB59.DBW2912.

In version V3.0.20 this value has to be 0. Thereby the monitoring, which is not 

yet 

implemented in this version, is deactivated.

Version 4.0 (*TM*)

- new coding. Previous versions were rejected.

  The structure and meaning of the interface has been retained unchanged.

Parameters:

ENABLE:         Actions in FC are only activated with ENABLE=1

                With ENABLE=0 the output values are cleared

PLUS_MINUS_EXTERNAL:1 in case the signals for plus/minus (DBX2920.0/.1) 

 are not set with direct keys. Used with a BHG or HT6

PLUS_KEY:       input byte of the right side (plus) direct keys

MINUS_KEY:      input byte of the left side (minus) direct keys

LS_DIRECT:      transfer word for direct key signals ( DB59.DBW2918 )