Siemens SPC3 Specifications download pdf (Page 10)

Introduction To ProfiBus DP

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Acromag, Inc. Tel:248-624-1541 Fax:248-624-9234 Email:sales@acromag.com http://www.acromag.com

During parameterization, a master sets up the communication and

monitoring times for the slave including the watchdog time (T

set by

Watchdog Factors in DU bytes 2 & 3 of the Set_Prm Telegram). The slave

ASIC implements a watchdog function where the slave will monitor the bus

communications with the master over time, and in the event of master failure

(timeout), the slave outputs go to a defined state. If the watchdog timer is

not retriggered by the slave station via bus communication with the master

within the time specified, then the slave will set its outputs to a defined state

and return to the Wait_Prm state (Wait For Parameterization). In setting

watchdog time T

, you need to consider the bus cycle time, plus a safety

factor for repeated telegrams (usually 25% minimum).

Before we examine slave operation in detail, we need to get a little

background information on a device’s GSD file and how the software is used

to build a ProfiBus system.

The GSD file is an electronic device data sheet or device data base file

that identifies the ProfiBus device. All ProfiBus devices (class 1 masters and

slaves) have their own GSD files. The GSD file is the fundamental building

block for the master parameter record. Use of the GSD file by a ProfiBus

configuration tool permits plug & play interoperability among different

devices from different manufacturers. This file does not reside within the

device itself, but usually on a separate disk/drive. It is an ASCII text file that

contains device-specific data, such as, vendor identification information,

supported baud rates, supported message length, number of input/output

data, meaning of diagnostic messages, timing information, plus options and

features supported, data formats, and available I/O signals. For modular

ProfiBus systems, a GSD file may contain several configurations (one for

each I/O module), one of which will be found valid during startup.

A GSD file is named by combining a vendor name identifier with the

device’s ident_ number. For example, “ACRO06F3.GSD” is used for the

Acromag 981PB-1012 device. The suffix “.GSD” denotes a language

independent GSD file. A “.GSE” file would specify an English file, “.GSF” for

French, “.GSS” for Spanish, “.GSI” for Italian, and “.GSG” for German.

The GSD file begins with the specifier “#Profibus_DP”. In the body of

the file, the parameters are specified as parameters of a keyword (as in

“keyword = parameter”, see below). Comment lines begin with a semicolon.

Case is not significant and the sequence of parameters is not important.

Lines are limited to 80 characters, but may be continued by placing a

backslash character “\” at the end of the line to be continued. A GSD file is

divided into sections as follows:

GSD FILES

1 2 ... 5 6 7 8 9 10 11 12 13 14 15 ... 37 38

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Siemens SPC3 Specifications Page 10

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