Block Format; Fcs Calculations - Omron E5ZE-8 Communications Manual

Block Format

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Block Format

1-3

FCS Calculations

Calculation Example
Transmission command
Command converted to ASCII code
FCS converted to ASCII code
Transmission code
The following format is used for the command and response blocks used in
E5ZE systems.
@
Unit no.
1
X16
Start
character 00 to 0F
Start Character:Each block begins with a start character, @ (40H).
Unit Number:
Header Code: The header code consists of two letters identifying the type of
Text:
FCS:
Terminator:
If the host computer is connected to more than one E5ZE for RS - 422 or RS -
485 communications, each of the E5ZE must have a unique unit number, oth-
erwise communications will not be possible.
Write a program for the host computer so that the host computer can calculate
the FCS in each command block and each response block to ensure problem -
free communications.
@
FCS = 40H (+) 30H (+) 30H (+) 52H (+) 58H (+) 30H (+) 30H (+) 30H (+) 30H = 4AH
40H
The result " 4A " is transmitted as the FCS of the transmission command.
* Symbols
H: Hexadecimal code
(+): Exclusive OR
X X
0
X16
Header
code (2 al-
phabetical
digits)
FCS calculation range
The unit number of the E5ZE is required so that the host
computer can identify the E5ZE.
command being sent.
The text consists of command or response data in detail.
The FCS is calculated as the exclusive OR of all characters
from the start character through the final data character. The
resulting 8 - bit data is converted to two ASCII characters for
transmission as an FCS.
Each block ends with a terminator consisting of * (2AH) and
a carriage return s (0DH).
FCS calculation range
0 0 R X
30H 30H 52H 58H 30H 30H 30H 30H
Text
0 0 0 0
FCS
34H 41H
Section 1-2
* s
X X
FCS Terminator
s
*
2AH 0DH
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