ICP DAS USA CAN-8823, User Manual

Page: 111 / 198

CAN-8x23 user’s manual (Revision 3.20, Ma r/08/2012) ------ 111
Step 3. In order to output 5V to the AO0 of the I-8024, users must send the
PDO message by using the 2nd RxPDO.
11-bit COB-ID (bit)
RTR
Data
Length
8-byte Data (byte)
Func Code Node ID
10 9 8 7 6 5 4 3 2 1 0 0 1 2 3 4 5 6 7
0 1 1 0 0 0 0 0 0 0 1 0 8 FF 3F 00 00 00 00 00 00
PDO
producer
PDO consumer
(CAN-8x23)
COB-ID
: 0x301
L
: 8
PDO-msg
: FF 3F 00 00 00 00 00 00
The first two bytes are for AO channel 0, and the others are for AO
channel 1, 2 and 3. Users need to transfer the float value to hex
format because only the CAN-8123/CAN-8223/CAN-8423 supports
the hex format. The output range of the I-8024 is -10V~10V.
According to the transformation table stored in the appendix table ,
the mapping hex-format range is from 0x8000 (-32768) to 0x7FFF
(32767). Therefore, the 5V is mapped to the 0x3FFF by applying
following equation.
 
FFF x
V V
V V
HexValue
3 0 16383 25 . 16383
) 32768 ( ) 32768 ( 32767
) 10 ( 10
) 10 ( 5
  
    






 
 

The first two bytes of the PDO message will be filled with “FF” and
“3F”. All the other AI channels are set to 0V. Then, the value “00 00”
will be given for these channels. For more details about how to
transfer the value between the hex and float, please refer to the
section 6.3.