User manual

Transferring Data Using Communication Blocks
138
33002479 06 07/2008
READ_REG
Function
Description
Upon request, the READ_REG block reads a register area once (rising edge of the
REQ input). It reads data from an addressed slave via TCP/IP Ethernet.
EN and ENO can be projected as additional parameters.
Symbol Block representation:
Parameter
Description
Description of block parameters:
Note: About this function block:
z When programming this function, you must be familiar with the routing
procedures used by your network.
z For technical reasons, this function block does not allow the use of ST and IL
programming languages.
READ_REG
REQBOOL
SLAVEREG
DINT
NO_REG
INT
AddrFld
WordArr5
BOOLNDR
BOOL
ERROR
WORD
REG_READ
WORD
STATUS
Parameter Data Type Meaning
REQ BOOL start read operation once
SLAVEREG DINT offset address of the first %MW word (4x register) in the slave
to be read from
NO_REG INT number of registers to be read from slave
AddrFld WordArr5 data structure describing the TCP/IP address
NDR BOOL set to 1 for one cycle after reading new data
ERROR BOOL set to 1 for one scan in case of error
STATUS WORD error code
REG_READ WORD first %MW word (4x register) for read values