11
iii)
TRANSMIT PROCESS DATA OBJECT [TPDO]
(Broadcast rate = 0.005sec, DLC=8)
TPDO1
CAN id byte 0 byte 1 byte 2 byte 3 byte 4 byte 5 byte 6 byte 7
0x180+NID NOx
(ppm)
O
2
(%)
TPDO2
CAN id byte 0 byte 1 byte 2 byte 3 byte 4 byte 5 byte 6 byte 7
0x280+NID
IP2 (A) disabled
IP1 (A) disabled
TPDO3
CAN id byte 0 byte 1 byte 2 byte 3 byte 4 byte 5 byte 6 byte 7
0x380+NID
RPVS (ohms) disabled
VHCM (V) disabled
TPDO4
CAN id byte 0 byte 1 byte 2 byte 3 byte 4 byte 5 byte 6 byte 7
0x480+NID
VS (V) disabled
VP2 (V) disabled
The table above shows the default TPDO assignments. Note that only NOx and O
2
are enabled
(see sections 8.7 Enable TPDO, 8.8 Disable TPDO and 8.9 TPDO MAPPING).
Each module can transmit up to four TRANSMIT PROCESS DATA OBJECTS (TPDO) at the
programmed TPDO broadcast rate (see section 8.6 to determine minimum broadcast rate). A
TPDO contains two data values; each data value corresponds to a measured parameter (e.g. NOx,
Lambda, AFR, O
2
, FAR, PHI, etc). These data values are referred to as PROCESS DATA
OBJECTS (PDO). Each PDO is a single precision 32 bit floating point number that conforms to
the IEEE-754 standard. All TPDO data is transmitted on the CAN bus least significant byte first
(Intel format).
The NID, TPDO Broadcast rate and TPDO mapping can be changed by the user.
Example: The following data was transmitted by the module with NID = 0x10 on TPDO1 and
contains 2 PDOs, NOx and O
2
.
TPDO1
CAN id byte 0 byte 1 byte 2 byte 3 byte 4 byte 5 byte 6 byte 7
0x190
0x00 0x80 0x4A 0x43 0xF2 0xFD 0x54 0x40
NOx = 0x434A8000 = 202.5
O2
= 0x4054FDF2 = 3.32800
Configuring which PDOs are transmitted in a particular TPDO is also known as TPDO
MAPPING and can be set by the user (see 8.9 TPDO MAPPING).