SENA ProBee-ZE20S User Manual

Page 34

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34

ProBee-ZE20S User Guide Rev.1.10

Unicast transmission timeout = (transmission retries + 1) x (transmission timeout)

Multicast and broadcast transmission timeout could be obtained by same way.

4.1.2

Multicast

Multicast transmissions are sent from a source device to destination devices with the specific group ID.

The group ID is assigned to the devices using the AT+GROUPID command. The AT command for the

multicast transmissions is as below.

AT+MULTICAST=<group_id>,<MSG><CR> or AT+MC=<group_id>,<MSG><CR>

, where <group_id> = group ID, <MSG> = data to transmit

The data transmission range can be set using the AT commands below. Please refer to the 9 S-Registers

for more details.

ATS36=n, where n is the radius.

ATS37=n, where n is the number of hops through nonmembers.

Note: ZigBee compliance rules prevents flooding of the network by limiting the network to a maximum of 9

broadcasts over 8 seconds. Attempts to submit additional broadcasts beyond this should result in the

transmission error. This is approximately one broadcast per second. It is, however, recommended to

broadcast one packet over 2 seconds for safe transmission. Broadcast transmission failure also causes

retransmission which is affected by transmission timeout(S33) and transmission retries(S32). Because

frequent retransmissions may cause to break the broadcast limitation, it is recommended to set more than

1000 for transmission timeout(S33) and set as small as possible for transmission retries(S32) .

Multicast data transmission is implemented on top of the network broadcast mechanism, so it is subject to

the same rules.

4.1.3

Broadcast

Broadcast transmissions are sent from a source device to all devices in the ZigBee network. The AT

command for the broadcast transmissions is as below.

AT+BROADCAST=<MSG><CR> or AT+BC=<MSG><CR>

, where <MSG> = data to transmit

The user can also specify the transmission range by changing the S35 register value as below. Please

refer to the 9 S-Registers for more details.

ATS35=n, where n is the broadcast range.

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