Siemens SIMATIC TIWAY 1 User Manual download pdf (Page 81)

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C-5

The next step will be to ensure that the module (station 2) has been set up

correctly by checking for proper network address, V Memory starting

address and redundant media setting. The way to do this is by using status

word 3 (WX3), and by masking off the bits which are not important for

information at the moment – bits 5-13. The result of WX3 after the unused

bits are cleared is then compared with the expected WX3 value. C1 is

turned on if the module configuration is correct; therefore, it can be used as

an indicator that the module has not been configured correctly

If the module configuration is correct, WX1 (network active list for Channel

A) is compared against the expected active list (V304). If this is correct, C3

is turned on. If C3 is off, this indicates that at least one Peerlink module

has logged off Channel A.

In using redundant media, WX2 should also be checked, therefore the next

step is to compare the expected active list against WX2. C4 will turn on if

this is correct. If C4 is off, this indicates that at least one Peerlink module

has logged off Channel B.

While C3 and C4 can be indicators that a station has dropped off the

network, it is necessary to determine exactly which station has logged-off

or if a faulty or broken connection is causing communication to switch from

Channel A to B. The following steps demonstrate this.

Since the network will be running on the channel with the most active

stations, it is necessary to check WX3 for operation on Channel A or B. If

Channel A is active, the value of WX1 will be loaded into V303 for later

comparison. If Channel B is active, the value of WX2 will be loaded into

V303. C2 will be turned on if Channel B is active. Since redundant media

will normally operate on Channel A this probably indicates a cable problem

or partial module failure on Channel A. C2 can therefore be used to

indicate a problem on Channel A. A counter may also be included here to

record the number of times the network is active on Channel B.

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Siemens SIMATIC TIWAY 1 User Manual Page 81