User`s guide

XBee RS-232 PH Adapter

Configuration

There are four key attributes of the Serial PH adapter’s firmware that allow

it to have a net charge on its batteries:

• Sleep Mode (SM)

•Idle Time (ST)

• Sleep Period (SP)

• Sleep Number (SN)

Sleep mode, determines what sleeping behavior the adapter has. By

default the adapter has cyclical sleep enabled. With cyclical sleep enabled,

if the adapter is idle (No RS-232 traffic, no transmit/receive) for the given

amount of Idle Time, it then performs Sleep Number amount of sleeping

cycles, each for the duration of the value of Sleep Period.

The default sleep mode settings are:

• SM = 4 (Cyclical sleep enabled)

• ST = 0x3E8 (Idle time of 1 second)

• SP = 0x40 (Each sleep period’s duration is 640 ms)

• SN = 1 (Perform 1 sleep period when sleeping)

For this configuration, the adapter would sleep for a total of 640 ms when

performing a sleep period, after it was idle for 1 second. During an RF

receive/transmit, the device is in an active state for a significant amount of

time, regardless of the Idle Time setting. If continuous requests/queries are

made to the device, it will stay in an active state, which can lead to a net

discharge of the battery, and eventually the adapter will become

unresponsive.

Adjusting the default settings is not recommended. Doing so can lead to

unit that will not power on. The fix is to remove the module from the adapter

and plug it into the serial line. Then, you can adjust these parameters

through X-CTU software. This software is available on the Software and

Documentation CD that accompanies Drop-in Networking kits and

ConnectPort X gateways.

The battery can take up to 24 hours to fully charge, and if the unit is run in

the worst-case scenario, no sleep mode enabled and continuously queried,

the battery has only a charge for around 40 minutes. After that, the unit will

become unresponsive. In addition, if the unit isn’t immediately put into a

sleep mode after the battery first becomes unable to power the adapter, the

battery will further deplete, and you will have to perform the fix mentioned

above to recover the device.

Data retrieval

Retrieving data from XBee adapters is done by issuing a remote AT IS

(Force Sample) command through the XBee API. The XBee API and AT IS

command are described in detail in the XBee ZNet 2.5 (Series 2) RF

Module data sheet. AT IS commands can be issued via a Python program

that is executed on the gateway. See also the Product Manual for the XBee

Module and the Digi Python Programming Guide.