70353C datasheet(56/76 Pages) MICROCHIP

56 / 76 page

dsPIC33E/PIC24E Family Reference Manual

DS70353C-page 21-56

21.7.5.1 FILTER COMPARISONS

Table 21-3 shows the filter comparisons configured by the DNCNT<4:0> control bits

(CiCTRL2<4:0>). For example, if DNCNT<4:0> = 00011, a message in which only the 11-bit SID

matches the SID acceptance filter (SID<10:0>), and bits 7, 6 and 5 of Data Byte 0 match the EID

filter (EID<2:0>) is accepted.

21.7.5.2 SPECIAL CASES

There may be special cases when the message contains fewer data bits than are called for by

the DeviceNet filter configuration:

• Case 1 – If DNCNT<4:0> is greater than 18, indicating that the user application selected a

number of bits greater than the total number of EID bits, the filter comparison terminates

with the 18th bit of the data (bit 6 of data byte 2). If the SID and all 18 data bits match, the

message is accepted.

• Case 2 – If DNCNT<4:0> is greater than 16, and the received message DLC is 2 (indicat-

ing a payload of two data bytes), the filter comparison terminates with the 16th bit of data

(bit 0 of data byte 1). If the SID and all 16 bits match, the message is accepted.

• Case 3 – If DNCNT<4:0> is greater than 8, and the received message has DLC = 1

(indicating a payload of one data byte), the filter comparison terminates with the 8th bit of

data (bit 0 of data byte 0). If the SID and all 8 bits match, the message is accepted.

• Case 4 – If DNCNT<4:0> is greater than 0, and the received message has DLC = 0,

indicating no data payload, the filter comparison terminates with the SID. If the SID

matches, the message is accepted.

Table 21-3:

DeviceNet™ Filter Bit Configurations

DeviceNet™ Filter

Configuration

(DNCNT<4:0>)

Received Message Data Bits to be Compared

(Byte<bits>)

EID Bits Used for

Acceptance

Filter

00000

No comparison

00001

Data Byte 0<7>

EID<17>

00010

Data Byte 0<7:6>

EID<17:16>

00011

Data Byte 0<7:5>

EID<17:15>

00100

Data Byte 0<7:4>

EID<17:14>

00101

Data Byte 0<7:3>

EID<17:13>

00110

Data Byte 0<7:2>

EID<17:12>

00111

Data Byte 0<7:1>

EID<17:11>

01000

Data Byte 0<7:0>

EID<17:10>

01001

Data Byte 0<7:0> and Data Byte 1<7>

EID<17:9>

01010

Data Byte 0<7:0> and Data Byte 1<7:6>

EID<17:8>

01011

Data Byte 0<7:0> and Data Byte 1<7:5>

EID<17:7>

01100

Data Byte 0<7:0> and Data Byte 1<7:4>

EID<17:6>

01101

Data Byte 0<7:0> and Data Byte 1<7:3>

EID<17:5>

01110

Data Byte 0<7:0> and Data Byte 1<7:2>

EID<17:4>

01111

Data Byte 0<7:0> and Data Byte 1<7:1>

EID<17:3>

10000

Data Byte 0<7:0> and Data Byte 1<7:0>

EID<17:2>

10001

Byte 0<7:0> and Byte 1<7:0> and Byte 2<7>

EID<17:1>

10010

Byte 0<7:0> and Byte 1<7:0> and Byte 2<7:6>

EID<17:0>

10011

•

11111

Invalid Selection

70353C датащи(PDF) 56 Page - Microchip Technology

70353C датащи(HTML) 56 Page - Microchip Technology

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76

датащи скачать

ссылки URL