Siemens SIMATIC NET Spécifications télécharger pdf (Page 14)

4 Siemens Simatic S7 Driver Online Help

What is a Timeout?

A timeout is the length of time the driver waits for a response from the process

hardware. When the driver does not receive a response within this interval, it times

out (gives up) and re-sends the data request.

You specify the driver’s timeout in the Reply Timeout field. Be sure you enter a time

that is adequate for the process hardware to respond.

For example, if it takes your hardware 1 second to receive data, 1 second to process it,

and 1 second to send the response, set the driver’s timeout value to 3 seconds or more.

Likewise, if you find that the driver frequently times out, increase the timeout interval

to allow your hardware more time to process its data requests.

In most 7.x drivers, the reply timeout is a device property.

Example

Suppose you want to read eight integer values from an S7 300 PLC. The device stores these

values starting with address DB3,1. You want to read the data every 5 seconds and update the

datablock for 15 seconds after requests stop.

Using this information, you specify the following for your datablock:

Start address: DB3,1

End address: DB3,8

Data type: BYTE

Poll rate: 5 seconds

Access time: 15 seconds

The datablock reads the following location in the device:

DB3,9DB3,8DB3,7DB3,6DB3,5DB3,3 DB3,4DB3,2DB3,1DB3,0

1 2 ... 9 10 11 12 13 14 15 16 17 18 19 ... 267 268

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Siemens SIMATIC NET Spécifications Page 14