ICP DAS USA CAN-8823, Руководство пользователя

Страница: 164 / 198

CAN-8x23 user’s manual (Revision 3.20, Ma r/08/2012) ------ 164
Step 6. In order to output 7V 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 98 59 00 00 00 00 00 00
PDO
producer
PDO consumer
(CAN-8x23)
COB-ID
: 0x301
L
: 8
PDO-msg
: 98 59 00 00 00 00 00 00
The first two bytes are valid for AO0. The other bytes are for AO1 to
AO3. And the output range of the I-8024 is -10V~10V. According to
the transformation table stored in the appendix table, the 7V is
mapped to the 0x5998 by applying following equation.
 
5998 0 22936 75 . 22936
) 32768 ( ) 32768 ( 32767
) 10 ( 10
) 10 ( 7
x
V V
V V
HexValue
  
    






 
 

The first two bytes of the PDO message will be filled in
“98” and “59”.
For more details about how to transfer the value between the hex
and float, please refer to the section 6.3.
Step 7. Although the AI input value has been changed according the AO value,
the RxPDO will not a utomatically reply in the CAN-8423. Therefore, users
have to use the RTR message from the 2nd TxPDO to read back the AI value.
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 0 1 0 0 0 0 0 0 1 1 0 00 00 00 00 00 00 00 00
PDO
consumer
PDO consumer
(CAN-8x23)
COB-ID
: 0x281