Description

This frame type is used to query or set queued command parameters on the local device. In contrast to Local AT Command Request - 0x08, this frame queues new parameter values and does not apply them until you either:

  • Issue a Local AT Command using the 0x08 frame

  • Issue an AC command—queued or otherwise

When querying parameter values, this frame behaves identically to Local AT Command Request - 0x08: You can query parameter values by sending this frame with a command but no parameter value field—the two-byte AT command is immediately followed by the frame checksum. When an AT command is queried, a Local AT Command Response - 0x88 frame is populated with the parameter value that is currently set on the device. The Frame ID of the 0x88 response is the same one set by the command in the 0x09 request frame.

Format

The following table provides the contents of the frame. For details on frame structure, see API frames.

Offset Size Frame Field Description

0

8-bit

Start Delimiter

Indicates the start of an API frame.

1

16-bit

Length

Number of bytes between the length and checksum.

3

8-bit

Frame type

Queue Local AT Command Request - 0x09

4

8-bit

Frame ID

Identifies the data frame for the host to correlate with a subsequent response.
If set to 0, the device will not emit a response frame.

5

16-bit

AT command

The two ASCII characters that identify the AT Command.

7-n

variable

Parameter value (optional)

If present, indicates the requested parameter value to set the given register at a later time.
If no characters are present, it queries the current parameter value and returns the result in the response.

EOF

8-bit

Checksum

0xFF minus the 8-bit sum of bytes from offset 3 to this byte (between length and checksum).

Examples

Each example is written without escapes (AP = 1) and all bytes are represented in hex format. For brevity, the start delimiter, length, and checksum fields have been excluded.

Queue setting local command parameter

Set the UART baud rate to 115200, but do not apply changes immediately.

The device will continue to operate at the current baud rate until the change is applied with a subsequent AC command.

The corresponding Local AT Command Response - 0x88 with a matching Frame ID will indicate whether the parameter change succeeded.

7E 00 05 09 53 42 44 07 16
Frame type Frame ID AT command Parameter value

0x09

0x53

0x4244

0x07

Request

Matches response

"BD"

7 = 115200 baud

Query local command parameter

Query the temperature of the module (TP command).

The corresponding Local AT Command Response - 0x88 frame with a matching Frame ID will return the temperature value.

7E 00 04 09 17 54 50 3B
Frame type Frame ID AT command Parameter value

0x09

0x17

0x5450

(omitted)

Request

Matches response

"TP"

Query the parameter