Siemens CP 1515 Manuel d'utilisateur télécharger pdf (Page 133)

(OLPLQDWLQJ5HGXQGDQW7UDIILF

Industrial Ethernet Wireless LAN RLM Manager, CP 1515 Manager

C79000-G8976-C171-01 133

Figure 24 The Hidden Station Problem illustrates an example of the “hidden

station” problem. Both station A and station B are within range of the

Access Point RLM however, station B cannot “hear” station A, therefore

station A is a “hidden station” for station B.

When station B starts to communicate with the Radio Link Module, it might

not notice that station A is already using the wireless medium. When station

A and station B send messages at the same time, they might collide when

arriving simultaneously at the Access Point RLM. The collision will most

certainly result in a loss of messages for both stations.

In situations as pictured Figure 24 The Hidden Station Problem, RTS/CTS

medium reservation may provide a solution to prevent message collisions by

handing over transmission control to the Access Point RLM.

Troubleshooting a “hidden station” problem usually provides the best results

when it is performed on the suspected stations that suffer from errors as a

result of the “hidden station” problem.

When configuring the PC Card CP 1515 parameters of an individual station

you can enable the RTS/CTS Medium Reservation parameter:

• To enable RTS/CTS Medium Reservation parameter, choose

$GG(GLW

FRQILJXUDWLRQSURILOH in the CP 1515 Manager, select the $GYDQFHG

tab and enable 576&760HGLXP5HVHUYDWLRQ.

You can enable RTS/CTS Medium Reservation on individual stations, i.e. the

setting of this parameter does not have to be the same for all SIMATIC NET

IWL equipped devices in your network.

1 2 ... 128 129 130 131 132 133 134 135 136 137 138 ... 298 299

Pas de commentaire

Siemens CP 1515 Manuel d'utilisateur Page 133