Mitsubishi Electric FX5 User Manual page 55

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 Description
Element Name Set the element name.
Code Type Select the data length type.
ASCII hexadecimal/HEX
Data Length Select the data length on the line.
The range is 1 to 4 bytes.
Data Flow Forward Direction
(Upper byte  Lower byte)
Reverse Direction
(Lower byte  Upper byte)
Byte Swap (by Word)
Calculating Start Select the start packet element number for the range to be calculated.
Range The range is 1 to 32.
End Select the end packet element number for the range to be calculated.
The range is 1 to 32.
*1 This can be selected only when the data length is set to 4 bytes.
• If there are no elements other than length, an element error occurs. (When using length, one or more
elements other than length are required.)
• If the calculation result exceeds the number of digits set with "Data Length", the excessive digit value is
discarded (invalidated). For example, if Data Length is 2 bytes and the data size calculation results are
"123" bytes, the data length will be "23".
• If there is a non-conversion variable (variable length)/non-verified reception (character length variable) after
the length, and that section is not included in the length calculating range, arrange the static data
immediately after the non-conversion variable/non-verified reception.
• When the code type setting is "ASCII Hexadecimal", a mismatch will occur if a character string other than
"0" to "9", "A" to "F", and "a" to "f" is received.
• Use "0" to "9" or "A" to "F" when converting to ASCII characters during send.
• When arranging multiple length elements, none of the length calculating range may overlap.
• When arranging multiple length elements, the previous length calculating range may not exceed the
arranged length.
• A length element cannot be arranged at the final position of the packet elements.
When sending: Sends the calculated length in order from the upper byte.
When receiving: Receives the data in order from the upper byte.
When sending: Sends the calculated length in order from the low-order byte.
When receiving: Receives the data in order from the low-order byte.
*1
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.
6 PREDEFINED PROTOCOL SUPPORT FUNCTION
Remarks



This cannot be set if the
data length is 1 byte.

53
6.3 Packet Elements
6