Cyclic Transmission; 32-Bit Data Guarantee - Mitsubishi Electric QJ71LP21 Reference Manual

6 PROGRAMMING

6.2 Cyclic Transmission

6.2.1 32-bit data guarantee

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The link scan of the remote I/O network and the sequence scan of the CPU module
operate asynchronously.
Thus, the link refresh executed per sequence scan is asynchronous with the link scan.
Depending on the timing of the link refresh, link data with data types of more than 32
bits (two words), such as the ones below, may be broken up into new and old data,
which may coexist in 16-bit (one word) units.
• Corrent values of analog-digital module
• Current values of positioning module, command speed.
The remote I/O network provides the following functions for making handling of the link
data easy.
• 32-bit data guarantee
• Block guarantee of cyclic data per station
32-bit data precision is guaranteed automatically by setting parameters so that the
following conditions 1) to 4) are satisfied.
If conditions 1) to 4) are not satisfied, a warning for 32-bit data separation is displayed
during setting with GX Developer.
1) The start device number of LB is a multiple of 20
2) The number of assigned LB points per station is a multiple of 20
3) The start device number of LW is a multiple of 2.
4) The number of assigned LW points per station is a multiple of 2.
Parameter settings for network assignment ranges
POINT
When you want to guarantee data larger than 32 bits (2 words), use the station unit
block assurance in Section 6.2.2.
: Section 6.2.1
: Section 6.2.2
.
H
MELSEC-Q
.
H
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