Rockwell-automation 900 Temperature Controller Communications Function Uživatelský manuál stáhnout pdf (Strana 17)

2-1 Publication 900-UM004D-EN-E - July 2010

Chapter

Bulletin 900 Communications Procedures

900-TCx (CompoWay/F)

Data Format

Unless otherwise indicated, numbers in this manual are expressed in

hexadecimal (with an H’ before the number: e.g., H’02). Values without the H’,

such as 00, are ASCII. The number underneath each delimiter in a frame

indicates the number of bytes.

Command Frame

BCC Calculation Example

The BCC (Block Check Character) is determined by calculating the exclusive

OR of the bytes from the node number up to ETX. The 8-bit result is written

to the BCC byte at the end of the frame.

Table 2.1

STX This code (H’02) indicates the beginning of the communications frame

(text). Always set this character in the first byte. When STX is received

again during reception, reception is carried out again from the point

where STX was received.

Node number • This number specifies the transmission’s destination.

• Specify the 900-TCx’s communication unit number.

• A BCD value between 00 and 99 or an ASCII value of XX can be set.

• Specify XX for a broadcast transmission. No responses will be

returned for broadcast transmissions.

• No responses will be returned from node numbers other than the

ones in the above range.

Sub-address This is not used on the 900-TCx. Be sure to set the sub-address to 00.

SID (service ID) This is not used on the 900-TCx. Be sure to set the Service ID to 00.

Command text Command text area. Refer to Structure of Command Text on page 2-5

ETX This code (H’03) indicates the end of the text.

BCC Block Check Character The BCC result is found by calculating the

exclusive OR of the bytes from the node number up to ETX.

STX

Node No.

12 2

Sub-address

0 00

SID

BCC Calculation Range

Tex t

Command Text

ETX

BCC

STX Node No. Sub-address SID Command Text ETX BCC

02H 0(30H) 0(30H) 0(30H) 0(30H) 0(30H) 0(30H) 5(35H) 0(30H) 3(33H) 03H 35H

BCC=30H

⊕

30H

⊕

30H

⊕

30H

⊕

30H

⊕

30H

⊕

35H

⊕

30H

⊕

33H

⊕

03H=35H

Calculation result 35H is set to the BCC area.

The

⊕ symbol indicates exclusive OR operation and the H indicates hexidecimal code.

1 2 ... 12 13 14 15 16 17 18 19 20 21 22 ... 102 103

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