Length - Mitsubishi Electric MELSEC iQ-RJ71EN71 User Manual

Length

The length code is used when there is an element that indicates the data length in the packet.
• When sending: Automatically calculates the data length in the specified range, and adds it to the packet.
• When receiving: From the received data, the data (value) corresponding to the length is verified as the specified range's
data length.
Length elements can be placed anywhere in the data part.
Multiple length elements can be set placed in one packet.
The following table lists the items.
Item
Element Name
Code Type
Data Length
Data Flow
Calculating Start
Range
End
*1 This can be selected only when the data length is set to 4 bytes.
1 FUNCTIONS
42
1.3 Communications Using the Predefined Protocol
Description
Set the element name.
Select the data length type.
ASCII Hexadecimal/HEX
Select the data length on the line.
The range is 1 to 4 bytes.
Forward Direction When sending: Sends the calculated length in order from the
(Upper Byte  Lower Byte)
upper byte.
When receiving: Receives the data in order from the upper byte.
Reverse Direction When sending: Sends the calculated length in order from the low-
(Lower Byte  Upper Byte)
order byte.
When receiving: Receives the data in order from the low-order
byte.
*1
Byte Swap (by Word) When sending: Interchanges the bytes in word units and sends the
calculated length.
When receiving: Interchanges the bytes in word units and receives
the data.
Select the start packet element number for the range to be calculated.
The range is 1 to 32.
Select the end packet element number for the range to be calculated.
The range is 1 to 32.
Remarks



This cannot be set if the data
length is 1 byte.
