ECM NH3CAN, Instruction Manual, Page: 11 / 35

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 NH3 (ppm) MODE (hex)
TPDO2 CAN id byte 0 byte 1 byte 2 byte 3 byte 4 byte 5 byte 6 byte 7
0x280+NID CEL1 (mV) CEL2 (mV)
TPDO3 CAN id byte 0 byte 1 byte 2 byte 3 byte 4 byte 5 byte 6 byte 7
0x380+NID RCL SCF
TPDO4 CAN id byte 0 byte 1 byte 2 byte 3 byte 4 byte 5 byte 6 byte 7
0x480+NID RPVS (ohms) VHCM (V)
The table above shows the default TPDO assignments. (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.
NH
3
). 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, NH
3
and MODE.
TPDO1 CAN id byte 0 byte 1 byte 2 byte 3 byte 4 byte 5 byte 6 byte 7
0x190 0x00 0x80 0x4A 0x43 0x78 0x42 0x00 0x00
NH3 = 0x434A8000 = 202.5
MODE
= 0x00004278 = 62
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).