User guide

5 - 23

PN 074-566-P1B

Composer Elite Operating Manual

5.5.2.1 Response Packet (Composer Elite to Host Message)

<Length><Command><Command ID><Sensor><Internal

Parameter><Status><Message><Checksum>

Length . . . . . . . . . . . . . . . . . . . . . . . 2 bytes Low / High (not including checksum

or length bytes). Numeric value representing

the number of characters in the response.

Two byte values, high and low order, are

required to represent this number. In order of

transmission, the low byte will precede the

high byte.

Command . . . . . . . . . . . . . . . . . . . . Reports the command sent by the host.

Command ID . . . . . . . . . . . . . . . . . . Reports the subcommand sent by the host.

Sensor . . . . . . . . . . . . . . . . . . . . . . . Reports the sensor number sent by the host.

Internal Parameter . . . . . . . . . . . . . Reports the parameter number sent

by the host.

Status. . . . . . . . . . . . . . . . . . . . . . . . Received as a hex value. Converted to Bits:

<ER><RS><BM><WA>. See Table 5-18.

Message . . . . . . . . . . . . . . . . . . . . . This field contains the data being sent to the

requesting application by Composer Elite.

This field is optional and the format of any

returned data is determined by the specific

command. Refer to section 5.6 for a detailed

description of all possible responses.

Checksum . . . . . . . . . . . . . . . . . . . . 1 byte, sum, modulo 256, of all bytes, not

including length and checksum. Modulo 256

is the numeric value from 0 to 255

representing the modulo 256 remainder of

the sum of the values of the ASCII codes that

comprise the response.

5.5.2.2 Communication Error Codes

If there was an error detected with the command sent to Composer Elite, the

response message will have the MSB of the status byte (SS bit) cleared (see Table

5-18 on page 5-24). The data portion of the message will be one byte long and will

be one of the following:

3 (0x03) . . . . Message length is zero*

10 (0x0A) . . . Invalid sensor number

11 (0x0B) . . . Invalid program number