Mitsubishi Electric MELSEC iQ-R User Manual page 207

CH1 Head pointer
Low speed
The buffer memory address of the oldest data of each channel in Logging data area (Un\G10000 to Un\G99999) can be
checked with this buffer memory area.
The offset value counted from the start address of each channel is stored.
■Buffer memory address
The following shows the buffer memory address of this area.
Buffer memory name
CH Head pointer
Ex.
When the value of 'CH2 Head pointer' (Un\G636, Un\G637) is 8550 with the following settings
• 'CH1 Logging data points setting' (Un\G536): 100 (10000 points)
• 'CH2 Logging data points setting' (Un\G736): 100 (10000 points)
In this case, the start address of CH2 is Un\G20000.
(1)
Un\G20000
(2)
Un\G28549
Un\G28550
Un\G29999
• At the first round of data logging, while data is being logged for the number of data points set in 'CH1
Logging data points setting' (Un\G536), the oldest data is stored in the start address of Logging data area
(Un\G10000 to Un\G99999). Thus, the value of 'CH1 Head pointer' (Un\G436, Un\G437) has been fixed to
0. As for data logging for points set in 'CH1 Logging data points setting' (Un\G536) + 1 and larger, the value
in 'CH1 Head pointer' (Un\G436, Un\G437) increases by one every time the data is stored.
• When 'CH1 Logging hold request' (Y1) is turned off, 'CH1 Head pointer' (Un\G436, Un\G437) is cleared to 0.
CH1
436, 437
(1) Logging data area
(2) Head pointer: 8550 (Offset value counted from Un\G20000)
(3) The latest data
(4) The oldest data (28550 = 20000 + 8550)
(3)
(4)
CH2 CH3
636, 637 836, 837
Appendix 3 Buffer Memory Areas
CH4
1036, 1037
A
APPX
205