User's Manual

Page 67 of 83

A Carrier Corp. Company

PART NUMBER T82002163

REV A

indicates an error. A list of valid status codes with their names and descriptions are in

the table below:

Status name Code Description

CMD_SUCCESSFUL 0x00 Returned upon successful completion of command.

CMD_UNKNOWN 0x02 The requested command is not part of the unit's API. This is returned

when a command does not exist.

BAD_INIT 0x07 The unit cannot be initialized due to erroneous information having been

stored in its configuration pages.

Depending on the command that was sent, the monitor may or may not send data after the

status code. For instance, if the high-speed download command is sent to the

monitor, the monitor will send all of the temperature data after the status code has

been sent.

The Omega TT4 also supports a new packet based command protocol which uses the

same basic structure as the Omega TT4 standard commands with the exception that

the command parameters and return data are in packet form with a checksum

attached. If the command has parameters then the host sends the command parameter

packet just after the monitor echoes back the command value. If the command

returns any data, then the monitor will return the data packet just after the status is

sent. The following figure illustrates this:

Executes

Command

Echo back command

0x00 or

Parameter Packet with

Checksum

Status

HOST PC MONITOR

TT4 Plus

PACKET

COMMAND

PROTOCOL

Data Packet With

Checksum