Siemens SIMATIC NET Especificaciones descargar pdf (Pagina 142)

132 Siemens Simatic S7 Driver Online Help

[3] If the device does not respond, the driver repeats step 2 until it receives a

response or it has exhausted all retry attempts. If SIMATIC NET cannot send

a message at any point while attempting to re-send the message, the driver

stops sending retry messages and proceeds to step 4.

[4] The driver marks the datablock as failed and waits the length of the delay time.

Once the delay time expires, the driver completes one of the following steps:

[a] If a back-up channel and device are specified, the driver switches to the

back-up device on the back-up channel. The driver sends the message

once to the new device without retries. If the back-up device on the

back-up channel does not respond, the driver switches back to the

primary device on the primary channel and the cycle repeats until a

device responds.

[b] If a back-up device is specified but a back-up channel is not specified,

the driver switches to the back-up device on the primary channel. The

driver sends the message once to the new device without retries. If the

back-up device does not respond, the driver switches back to the

primary device and the cycle repeats until a device responds.

[c] If a back-up channel and a back-up device are not specified, or if a back-

up channel is defined but a back-up device is not specified, the driver

waits the delay time and re-initiates the polling process with the primary

device on the primary channel.

[5] The device may have multiple datablocks. In this situation, the driver uses its

QuickFail logic and marks all datablocks on that device as failed and moves

on to the next device. The next time the driver attempts to send the message to

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Siemens SIMATIC NET Especificaciones Pagina 142