Problem using SFC67 and SFC68 (x_get, x_put)

metaller

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• May 31, 2005

• #1

Hello there, i need a small help with using scf67 and 68 in s7-300 CPU connected to s7-200 CPU... How could i know when is the communication between these CPUs down?
Thanx for help...

 

SimonGoldsworthy

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Mar 2005

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England

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• May 31, 2005

• #2

You could put heart-beat bits into the data areas you are transferring. If the heart-beats stop changing then you know the comms is down. Note the heart beat must not change faster than half your comms rate to prevent aliasing.

 

metaller

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• May 31, 2005

• #3

thats exactly the problem... with this solution could i know if PLC is in stop mode, but when the communication crashes down, the last data transmitted from CPU are remembered and showed...

 

aloudermilk

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Jun 2005

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• Jun 1, 2005

• #4

s7-200 - S7-300

You must write your code so these heartbeat bits are required to toggle every x number of milliseconds or a communication error will result

 

metaller

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• Jun 3, 2005

• #5

I've solved it... I'm writing to S7200 1 and 0 with 1s period, and then reading it in S7300. When a positive edge arrives i'm reseting one timer... When does not, timer elapses and a comm error is set...