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Binary command language appendix a, Circuit control request (ccr) – Rockwell Automation 1775-S5_SR5,D17756.5.5 User Manual PLC-3 FAMILY I/0 User Manual

Page 132

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1

0

0

0

X

X

X

X

reset communications

reset response block seq cntr

reset command block seq cntr

set timeout value

Binary Command Language

Appendix A

A-4

Circuit Control Request (CCR)

The master uses the circuit control request (CCR) to initiate, reset, or
verify communications with the scanner. The CCR consists of five bytes
of data defined as follows:

STX Control Code

Character

Checksum

Timeout Value

ETX

Command:

Description:

STX (start of text)

the first byte of the control block (02 hex).

Control code

In the control code byte, bits 7, 6, 5, and 4 contain the value 1, 0,

0, and 0 respectively. This is necessary for the scanner to

recognize the byte as a control code. The meaning of the other

bits in the control code is as follows:

Character Timeout Value

The third byte is the character timeout value. If bit 3 in the above

control code is set, this byte sets the character timeout value. The

timeout is 10 ms times the value in this byte, which allows timeout

values between 10 and 2550ms. If bit 3 in the control code is not

set, this byte is zero. A zero in this byte causes a default

character timeout as shown in Table A.A.

ETX (End of Text)

03 hex.

Checksum

The fifth and last byte in the CCR is a checksum. The checksum

is the least significant eight bits of the sum of the previous four

bytes in the CCR.