ELM327_1 Datasheet, PDF (41/51 Pages) ELM Electronics – OBD to RS232 Interpreter

ELM327
Programmable Parameters (Cont’d)
PP
Description
Values Default Type
29 Printing of the CAN data length (DLC) when printing header bytes 00 = ON
FF = OFF
FF
(OFF)
D
(see note 2)
2B Protocol A (SAE J1939) CAN baud rate divisor.
01 to 40
02
R
(250 Kbps)
The protocol A CAN baud rate is determined by this value (rate in
kbps = 500/value). For example, setting this PP to 19 (ie. decimal
25) provides a baud rate of 500/25 = 20 kbps.
2C Protocol B (USER1) CAN protocol options.
Each bit of this byte controls an option, as follows:
00 to FF
E0
R
(11100000)
b7: Transmit ID Length, 0=29 bit ID, 1=11 bit ID
b6: Data Length, 0=fixed 8 byte, 1= Variable DLC
b5: Receive ID Length, 0=as set by b7, 1=both 11 bit and 29 bit
b4: reserved for future - leave set at 0
b3: reserved for future - leave set at 0.
b2, b1, and b0 determine the data formatting options, as follows:
b2 b1 b0 Data Format
000
none
001
ISO 15765-4
010
SAE J1939
Other combinations are reserved for future – results might be
unpredictable if you should select one of them.
Note that b7 is the msb, and b0 is the lsb. For example, the default
value of E0 can be shown as 11100000 in binary, which has b7, b6
and b5 set to 1’s. This means that by default, 11 bit IDs will be
sent, the data length will vary, and the ELM327 will receive
messages with either 11 or 29 bit IDs.
2D Protocol B (USER1) baud rate divisor. See PP 2B for a description. 01 to 40
04
R
(125 Kbps)
2E Protocol C (USER2) CAN options. See PP 2C for a description.
00 to FF
80
R
(10000000)
2F Protocol C (USER2) baud rate divisor. See PP 2B for a description. 01 to 40
0A
R
(50 Kbps)
Notes:
1. The “Type” column indicates when changes to the Programmable Parameter take effect. Possible values
are:
I - the effect is immediate,
D - takes effect after Defaults are restored (AT D, AT Z, AT WS or power off/on)
R - will only become apparent after a Reset (AT Z, AT WS or power off/on)
P - only takes effect after power off/on or AT Z.
2. These are changes since the last version of the IC.
ELM327DSC
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