Mitsubishi Electric MELSEC-Q series User Manual page 133

(43)CH Head pointer (Un\G1090 to Un\G1097)
The buffer memory address where the oldest data is stored can be checked in CH Logging data (Un\G5000 to
Un\G44999) for each channel. The difference between the buffer memory address where the oldest data is stored
and the start address in CH Logging data (Un\G5000 to Un\G44999) is stored.
For details on the logging function, refer to the following.
Logging Function (
When the value of CH2 Head pointer (Un\G1091) is 3551
Ex.
● The oldest data is stored in the start address of CH Logging data (Un\G5000 to Un\G44999) while the first 5000 data is
logged from when the logging is started. Therefore, the value in CH Head pointer (Un\G1090 to Un\G1097) is fixed to 0.
After the 5001st data, the place of CH Head pointer (Un\G1090 to Un\G1097) moves one by one.
● When CH Logging hold request (Un\G1008 to Un\G1015) is turned OFF (0), CH Head pointer (Un\G1090 to
Un\G1097) is cleared.
Page 58, Section 4.12)
CH2 Logging data
Un\G10000
Latest data Un\G13550
Un\G13551
Un\G14999
CHAPTER 6 BUFFER MEMORY
Oldest data
13550 = 10000 + 3550
6
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