Obvius A89DC-08 - Manual (Page 12)

20 40021 INT16 channel 3 current, long average AMPS * 100
21 40022 INT16 channel 4 current, long average AMPS * 100
22 40023 INT16 channel 5 current, long average AMPS * 100
23 40024 INT16 channel 6 current, long average AMPS * 100
24 40025 INT16 channel 7 current, long average AMPS * 100
25 40026 INT16 channel 8 current, long average AMPS * 100
System information points :
------- ------- ------- ----- --------------------
offset point type rw/ro desc
1000 41001 UINT16 ro Serial Number (bytes 1,2)
1001 41002 UINT16 ro Serial Number (bytes 3,4)
1002 41003 UINT16 ro Serial Number (bytes 5,6)
1003 41004 UINT16 ro firmware version major
1004 41005 UINT16 ro firmware version minor
1005 41006 UINT16 ro mfg date MSW
1006 41007 UINT16 ro mfg date LSW
1007 41008 UINT16 ro up time (seconds) MSW.
1008 41009 UINT16 ro up time (seconds) LSW.
1009 41010 UINT16 rw Our Modbus address (1-247)
1010 41011 UINT16 ro Hardware Version (8908)
1011 41012 UINT16 ro PCB Rev (0=rev A, etc) (low byte Part Rev)
1012 41013 UINT16 rw Minimum current threshold for alarm feature, amps * 100.
eg 1234 = 12.34A (x100, 0 to 50 amps)
1013 41014 UINT16 rw deviation threshold for alarm feature, percent * 100.
eg 1234 = 12.34% (0 to 100%)
1014 41015 UINT16 rw deviation minimum time for alarm feature, in seconds.
(0 to 3600 seconds)
1015 41016 UINT16 rw Channel disable: Bitmap of channels to disable
(0x00 = all 8 enabled, 8 bit: 0x00 to 0xFF)
1016 41017 UINT16 w Ave-clear: write any value to clear long average.
(read returns zero)
1017 41018 INT16 ro Internal Powersupply, +12v rail. (x100, eg 1234 = 12.34v)
1018 41019 INT16 ro Internal Powersupply, -12v rail. (x100, eg 1234 = 12.34v)
1019 41020 UINT16 ro reason for reboot. 0x01=POR, 0x02=EXTR 0x04=WDTR 0x08=BODR,
0x8000=WDTOF
Register formatting
The Modbus data register set includes both 16 and 32 bit values, as well as signed and unsigned numbers. On Modbus
systems that do not allow you to read 32bit values, you can calculate the pulse count as follows:
Total = (MSW * 65536) + LSW
When using C or other programming languages, you can combine them with bit shifting and xor.
Total = (MSW << 16) | LSW;
It is important to read both the MSW and LSW values in a single Modbus read request. Use the Modbus function 0x03 to
read all the Modbus data registers in a single block, and then assemble the data point values from the Modbus registers
received in the query. If the MSW and LSW values are read in separate queries, the value may be updated between Modbus
queries and the resulting combined number may be incorrect.
Data points such as the total and per-channel current measurements are provided as signed values to represent both positive
and negative current flow. A positive value represents current flow in the direction of the arrow on the top of the hall effect
sensor. Signed values are encoded in standard two's compliment format.
Page 12 A89DC-08 – DC Current Monitor