THERMOCOUPLE 3N5991 - Caterpillar

Each Parameter Identifier (PID) is two bytes in length. The Parameter Identifier is hexadecimal. The PID is followed by data bytes. The data bytes are represented as aa for one data byte or aabb for two data bytes, or mb for multiple bytes. For example, the CCM Error Code PID is $00 $82. The error code is followed by two bytes of data (ab) that contain the CCM fault information. Data bits are given in binary form unless the number is preceded by $. All data is sent with the most significant byte (MSB) first.The following chart is a quick reference list of the Parameter Identifiers (PID). The chart also contains a brief description of the Parameter Identifiers.
Table 1
QUICK REFERENCE CHART WITH DESCRIPTION OF GENERAL PARAMETER IDENTIFIERS    
PID     Description    
$00 $0D
a     Remote Fault Reset
Used to reset faults on the CCM.    
$00 $80
aabbcc     Device ID Code
Used to read the device ID code from the CCM as well as from other components on the data link. Each pair of bytes (aa, bb, cc) is sent LSB first.    
$00 $82
ab     CCM Error Codes
Used to read the CCM error codes.    
$AA $12
a     CCM Communication Rate Change Enable
Used to determine if the CCM is connected to the host computer directly or remotely using a modem. Also used to enable or disable the host computers ability to change the communication rate of the RS-232C serial port.    
$AA $87
aaaaaaaa     Access Level 1 Password
Used to read or program the Level 1 Password    
$AA $88
aaaaaaaa     Access Level 2 Password
Used to read or program the Level 2 Password    
$AA $89
aaaaaaaa     Access Level 3 Password
Used to read or program the Level 3 Password    
$AA $8A
aaaaaaaa     Login Password
Password used to login when host device is connecting to the CCM    
$F0 $12
aa     Security Access Level
Used to read or program the password level.    
$F6 $01
aabb     CCM RS-232C Serial Port Configuration
Used to program the RS-232C port configuration on the CCM    
$F8 $14
aaaaa aaaaa     Application Software Part Number
Used to read and write the application software part number for the CCM.    Remote Fault Reset$00 $0D aUsed to reset faults on the CCM.
Table 2
(a)     $00 - $7F = Retain current CCM inactive fault status.
$80 - $FF = Reset CCM inactive fault.    Device ID Code$00 $80 aabbccUsed to read the device ID code from the CCM as well as other components on the data link. Each pair of bytes (aa, bb, cc) is sent LSB first.
Table 3
(aa)     Module ID: will always equal $61, data will be sent as $61 $00    
(bb)     Service Tool Support Change Level: $01, data will be sent as $01 $00    
(cc)     Application type:$FF $E0, data will be sent as $E0 $FF    CCM Error Codes$00 $82 abUsed to read the CCM Error Codes.
Table 4
(a)     bit 1 = Reserved    
(b) (1)     Fault Code Status    
bit 8