Mitsubishi Electric MELSEC iQ-R Series User Manual page 133

CH1 Head pointer
The buffer memory address of the oldest data in CH1 Logging data (Un\G10000 to Un\G10999) can be checked with this
buffer memory area.
The offset value at the start address of CH1 Logging data (Un\G10000 to Un\G10999) is stored.
■Buffer memory address
The following shows the buffer memory address of this area.
Buffer memory name
CH Head pointer
CH Head pointer (in Q compatible mode)
Ex.
When the value of 'CH2 Head pointer' (Un\G634) is 8550
Head pointer: 550
(offset value from Un\G11000)
• Until the first 1000 points of data is logged from the beginning of logging, the value in 'CH1 Head pointer'
(Un\G434) is fixed to 0 since the oldest data is stored in the start address of CH1 Logging data (Un\G10000
to Un\G10999). On and after the 1001st data, 'CH1 Head pointer' (Un\G434) increases one by one each
time data is stored.
• When 'CH1 Logging hold request' (Un\G471) is turned on and off, 'CH1 Head pointer' (Un\G434) is cleared
to 0.
CH1 CH2 CH3
434 634 834
1090 1091 1092
CH2 Logging data
Un\G11000
The latest data
Un\G11549
The oldest data
Un\G11550
11550 = 11000 + 550
Un\G11999
CH4 CH5 CH6
1034 1234 1434
1093 1094 1095
Appendix 3 Buffer Memory Areas
CH7 CH8
1634 1834
1096 1097
A
APPX
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