CM (Channel Mask)

This command applies to the XBee/XBee-PRO SX RF Module.

CM allows you to selectively enable or disable channels used for RF communication. This is useful to avoid using frequencies that experience unacceptable levels of RF interference, or to operate two networks of radios on separate frequencies.

When CM is queried, it returns the operating channel mask based on what value BR is set to. When BR is set to 2, a fixed channel mask is used (see the defaults below). A user-defined CM value is only used when BR is set to 0 or 1.

This command is a bitfield. Each bit in the bitfield corresponds to a frequency as defined in the AF (Available Frequencies) command. When you set a bit in CM and the corresponding bit in AF is 1, then the device can choose that channel as an active channel for communication.

Note For Australia and New Zealand, CM is read-only.

Exactly MF (Minimum Frequencies) number of channels must be made available for the device to communicate on.

All devices in a network must use an identical set of active channels in order to communicate. Separate networks that are in physical range of each other should either be configured to use separate channels or to use different HP (Preamble ID) and/or ID (Network IDs) to avoid receiving data from the other network.

You may find the ED (Energy Detect) command useful when choosing what channels to enable or disable.

The default CM mask spaces the channels across the entire 900 MHz band.

Parameter range

United States/Canada: 0x1 FFFF FFFF FFFF - 0x1F FFFF FFFF FFFF FFFF FFFF FFFF

Australia/New Zealand: Read-only

Brazil: 0x03 FFFF FFFF FFFF - 0x1F FFFF FFFF FFFF FFFF

Default

Country	Default CM when BR is 0 or 1	Default CM when BR is 2
United States/Canada	0x05 5555 5555 5555 5555 5555 5555	0x00 0000 0000 0003 FFFF FFFF FFFF
Australia	0x00 0000 0000 0000 01FF FFFF FFFF	0x00 0000 0000 0000 0000 00FF FFFF
New Zealand	0x00 0000 0000 0000 01FF FFFF FFFF	0x00 0000 0000 0000 0000 0000 07FF
Brazil	0x00 0000 001F FFFF FFFF FFF8 0000	0x00 0000 0000 0000 0007 FFFF FFFF