Specifications

Conﬁguring the PLC Section 4-3

d) Floating Point Number

The data are interpreted in the Siemens ﬂoating point format.

e) Binary Variables with a Length of 1, 2 or 4 Bytes

Data with a length of 2 bytes are interpreted in the PLC-conformal byte order for

words.

Data with a length of 4 bytes are interpreted in the PLC-conformal byte order for

long words.

4.3 Conﬁguring the PLC

Before a communication between the operating terminal and the Siemens PLC is

possible, the supplied function blocks must be installed and executed during the

PLC start-up or at cyclic intervals, respectively, and a communications data block

must be speciﬁed in the RAM of the PLC.

4.3.1 Status Data Area

In addition to the random read and write access to PLC variables, an area compris-

ing 6 words (DW70 - DW75) is available in the data block which allows the PLC to

inﬂuence the terminal (status data area). The transmission of the entire area to the

terminal is activated as soon as the value 128 is written into DL69. After the trans-

mission, DL69 will be reset to 0 by the FB201.

The status data area is word-structured and has been assigned to ﬁxed addresses:

DL70 : Write coordination byte

DR70 : Reserved

DW71 : Sequential message channel

DW72 - DW76 : LED-bits for function keys

4.4 Error Messages

Code 1 E SLAVE NOT READY ..........The slave address has been

sent, however, no response has

been received within the speci-

ﬁed time period of 5 seconds.

Possible causes for the error:

- Incorrect slave address.

- No hardware connection.

FRAME .........................The SIO has detected a framing

error.

Possible cause for the error:

- Incorrect interface parameter in the terminal or in the PLC.

TIMEOUT.......................After successful completion of

the addressing phase and after

sending the telegram from the

terminal to the PLC, the re-

sponse telegram from the PLC

has not been received within

the bus monitoring time period

of 300 ms.