Feig Electronic OBID i-scan ID ISC.M02.M8-B, Руководство пользователя

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OBID i-scan
®
System-Manual ID ISC.M02.M8-B
FEIG ELECTRONIC GmbH Page 10 of 43 H90400-0e-ID-B.doc
Data format:
Start bits: 1
Data bits: 8
Stop bits: 1
Parity: even
odd
none (default)
Timing conditions:
Starting delay:
Before sending a starting sign (length byte) of a protocol, there must be a delay of
minimum 5 ms.
Host
→
Reader:
.. Reaction time Starting delay .. ..
Õ
5...n ms
Ö Õ
min. 5 ms
Ö
Host
←
Reader:
.. .. ..
Data timeout:
Within one protocol, the characters have to follow each other in intervals of maxi-
mum 12 ms.
Õ
max. 12 ms
Ö Õ
max. 12 ms
Ö Õ
max. 12 ms
Ö
Host
→
Reader:
Char n Char n+1 Char n+2 ..
2.2. CRC16 Calculation Algorithm
Polynom: x
16
+ x
12
+ x
5
+ 1
⇒
CRC_POLYNOM = 0x8408;
Start Value: 0xFFFF
⇒
CRC_PRESET = 0xFFFF;
C-Example:
unsigned int crc = CRC_PRESET;
for (i = 0; i < cnt; i++) /* cnt = number of protocol bytes without CRC */
{
crc ^= DATA[i];
for (j = 0; j < 8; j++)
{
if (crc & 0x0001)
crc = (crc >> 1) ^ CRC_POLYNOM;
else
crc = (crc >> 1);
}
}