Integration Guide

WIT2410

When a remote links to a base and requests registration, it requests by default that it be

assigned handle 30H. This default request can be changed by the Set Default Handle

command. If that handle is not currently in use by another remote, the base will assign

that handle to the remote. If the requested handle is already in use by another remote, the

base will assign the next higher handle that is available. Thus, if a remote requests handle

30H and that handle is already assigned, the base will assign the remote handle 31H if

that is available. If 31H is already assigned, the base will assign handle 32H is that is

available and so on.

When a remote leaves the coverage area of the base or otherwise loses link, e.g. the

remote was turned off or put into sleep mode, the base detects this event when the remote

does not renew its registration within 255 hops. With the default setting of 10msec per

hop, this could be as along as 2.55 seconds. If within this time the remote re-establishes

link with the base, the previous handle assigned to this remote will still be marked active

in the base radio. Thus the remote will be assigned a new handle. If the base radio is in

one of the protocol modes, a new CONNECT packet will be issued indicating the current

handle assigned to the remote. The remote is identified by the serial number that is

contained in the CONNECT packet.

If the radio is to be used in a point-to-point mode where there is only one base and one

remote, using the point-to-point mode command of the radios will override this handle

mechanism and always assign the remote the same handle.

2.2.4. TDMA Operation

For applications needing guaranteed bandwidth availability, the TDMA operation of the

WIT2410 can meet this requirement. In the WIT2410 TDMA scheme, each remote has

an assigned time slot during which it can transmit. The base station time slot is set

independently of the remote time slots through the Set Base Slot Size command. The

base station assigns each remote a time slot and informs the remotes of the size of the

time slot. All remote time slots are the same size that is determined by the number of

remotes registered with the base station. The slot size is a dynamic variable that changes

as the number of registered remotes changes. The remotes are continually updated with

the time slot size. This approach continually maximizes the data throughput. The base

station divides the amount of time available per hop by the number of registered remotes

up to a maximum of 16 times slots per hop. If the number of registered remotes is greater

than 16, the time slots will be spread across the required number of hops. For networks

with more than 16 possible remotes, the Set Duty Cycle command must be used to specify

a duty cycle -- the number of hops over which the time slots must be spread. For 1 to 16

remotes, no duty cycle is required; for 17 to 32 remotes a duty cycle of at least ½ is

required; and for 33 to 62 remotes a duty cycle of ¼ or more is necessary. An added

benefit of using the power save mode to set a duty cycle is improved average current

consumption efficiency. Refer to the Status Commands section for details of this

command.