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4.3 Requests to the DN611

(b) Polling transmission mode = 1

• The master device checks the polling slave devices for response and makes

a polling request to the individual slave devices in sequence. If there is no

polling response from a slave device, the master device waits for 20 ms

before making a polling request to the next slave device.

• If a slave device does not respond till timeout is repeated three consecutive

times, the slave device is erased from the communicating node list of the

DN611 . This allows the DN611 to continue transmission to the remaining

slave devices in normal operation, without wait time for response.

• Only the slave devices which have failed to respond for three consecutive

timeouts will be erased from the communicating node list. If a slave device

has not responded for two consecutive timeouts but but responded in the

next scan, the number of timeouts for no response is cleared.

• The DN611 periodically checks the slave devices erased from the communi-

cating node list for response and, if any of them responds, it is registered

again on the communicating node list.

• If an n number of slave devices do not respond simultaneously, the real scan

cycle till three consecutive timeouts is as follows:

Real scan cycle = Real scan cycle in normal operation + n number of

slave devices x 20 ms

(6) Bit-strobe slave devices without response

The master device makes a bit-strobe request regardless of whether polling

transmission mode is selected, and waits for bit-strobe response from a slave device

for 20 ms after making the request. After the 20 ms of waiting for response, the

DN611 starts the next scan.

• As long as there is a slave device which does not respond, the master device

waits 20 ms for response every scan.

• The real scan cycle in cases where there is a slave device which does not

respond is expressed as follows:

Real scan cycle = Real scan cycle in normal operation + 20 ms

Usage Recommendations

1. Set a DN611 node address smaller than the node addresses of slave devices (because of the

characteristics of the CAN used for the DeviceNet).

Toshiba 2000 V Series User Manual

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