Mitsubishi Electric MELSEC iQ-RJ71C24-R2 - NULL Characters Removal for Send Data Using Bidirectional Protocol

25 AUTOMATIC REMOVAL OF NULL CHARACTERS INCLUDED IN SEND DATA
25.5 NULL Characters Removal for Send Data using Bidirectional Protocol
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25.5 NULL Characters Removal for Send Data using
Bidirectional Protocol
This section explains automatic removal of NULL characters to data to be transmitted using the bidirectional protocol.
Target range of automatic removal of NULL characters
The send data range to which automatic removal of NULL characters is performed is as shown below. However, the automatic
removal of NULL characters is not performed when a response message is transmitted.
When data is transmitted, C24 performs the processing as follows:
• Range of automatic removal of NULL characters
C24 performs the automatic removal of NULL characters to an arbitrary data portion of a message (data length is not
included).
• Automatic removal of NULL characters in data portion
C24 deletes NULL characters included in send data, and then transmits data.
• Handling of sum check code
The results of adding the data portion after automatic removal of NULL characters as binary code data are added to the
transmission message as sum check code.
*1 Calculation of sum check code is shown below:
Precautions
When the automatic removal of NULL characters is performed to data transmitted using the bidirectional protocol, always
specify the "Word/byte units designation" to "Byte units".
E
N
Q
Target range of NULL characters automatic deletion
(Arbitrary data)
Sum check
code
Message for data
transmission
Data length Data portion
*NULL characters automatic deletion is disabled when transmitting a response message.
(*1)
E
N
Q
05
H
32
H
01
H
31
H
62
H
00
H
43
H
42
H
41
H
33
H
06
H
LH
123ABC
LH
(H) (L)
(0008
H
)
00
H
08
H
(3231
H
)
32
H
31
H
(0033
H
)
00
H
33
H
(4241
H
)
42
H
41
H
(0043
H
)
00
H
43
H
Sum check code is calculated
from the data portion/data
length after NULL characters
automatic deletion, and added.
Buffer memory (transmission area)
(When byte units are used)
Message
Transmission
data count
Data
length
(0003)
Sum
check
code
Data portion
NULL
characters
automatic
deletion
Transmission
data
(The data count is in word units)
Data length after NULL characters
automatic deletion is added.
(H)(L)
06H+00H+31H+32H+33H+41H+42H+43H=0162H