Extended Memory; Table 25 - Channel Detail; D.7 E Xtended M Emory - Geokon 8800-2-1A Instruction Manual

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Data can be collected from the Node tables at a query interval equal to or less than the scan
interval. Readings will appear in the Node tables as soon as they are successfully communicated
from each Node to the Supervisor. The contents of channel zero through channel nine depends
on the code at offset four (address 0xE95 in this example).
It is possible to miss data if only querying the Node tables. If two successive data packets for a
particular Node arrive, only the second one will be stored in the Node table, regardless of the
time stamps.
Table 25 - Channel Detail (Single Channel Node)
Readings that fall on odd times (not on the scan interval) will have zero as the data array number
to distinguish them from normal readings. When a Node first joins the network with a valid scan
rate and time, it will take a reading at the top of the next minute, regardless of the scan rate.
These readings may fall on odd times.
D.7 Extended Memory
When using Multiplexers, only Node data with code 0xD0 will reside in the Node data table
(Table 24 on the previous page). To access all historical data, Modbus masters must be
programmed to read the extended memory in the Supervisor. Extended memory is divided up
into 1,048,576 readings of 16 registers (32 bytes) each. Data read from external flash needs to be
treated according to the code stored in the first byte of the first register.
The 16 register reading detail is shown in Table 26. The first external memory data array starts at
Modbus register 0x40000 (Page = 4, Address = 0) and the last at 0x103FFF0 (Page = 0x103,
Address = 0xFFF0).