User's Manual

There are three cases in which the data buffer may become full.

1) Since the 9600 and 19200-baud modules support serial interface rates from 2400-57600

bits/second, the serial data rate could be configured at a higher rate than the module’s

over-the-air baud rate. If this happens, long serial data streams can cause the data buffer

to become momentarily full, causing *CTS to de-assert.

2) Since the 24XStream modules are half-duplex, they can either receive or transmit at a

given time. If a long string of over-the-air data is received, serial data could arrive at the

buffer and cause it to become full if the module is unable to transmit the data.

3) If any module in a network (see “Networking and Addressing”) is transmitting data, all

other modules in the network will not transmit until they finish receiving data. Thus, if

they receive serial data, their data buffers could become full.

In some applications, where none of these conditions will occur, the *CTS signal need not be

monitored.

RTS/CMD – Pin 5 (Input)

RTS

The RTS signal (request to send) is not implemented for flow control with the 24XStream

modules. All received data (over-the-air) is sent out the serial port regardless of the RTS signal.

CMD

The 24XStream comes with a variety of configurable settings including power-saving modes and

network addressing options. This pin can be used as one way to manually configure the

24XStream module as described in the “Command Mode” section. When this pin is driven high

(asserted), incoming serial data (on the DI pin) is interpreted as commands instead of data. See

the “Command Mode” section for more information.

*CONFIG – Pin 9 (Input)

The (low-asserted) *CONFIG pin is used to force the module to enter AT Command Mode.

When asserted, the serial port baud rate is temporarily set to match the default baud rate of the

24XStream module. This assures that the module will transition into AT Command Mode at a

known baud rate. Upon entering AT Command Mode, all configured parameters, including the

baud rate, remain in their saved state and can be modified as described in the “AT Command

NOTE: DO NOT tie the *CONFIG pin to an external device as it may cause problems with

module operation. The *CONFIG pin should be tied to an external switch and used manually to

enter AT Command Mode only when AT Command Mode cannot be entered under the normal

procedure (see “AT Command Mode” section).