Special Reading Of Indication Bits - ABB Relion 620 Series Protocol Manual

1MRS757645 B
3.5.3.3
620 series
Communication Protocol Manual
>25R146I42:CC
<25D:F025A476:CC
The SPA implementation has no way of checking that the two Modbus registers
actually belong together as one value. Any two independent consecutive 16 bit
registers can be read freely in one 32 bit data value packet.

Special reading of indication bits

Many Modbus indications (one bit data) in the device are coded as MOM and MCD
bit pairs. The Master detects a fast indication 0￫1￫0 change, if the two bits are
combined with logical OR operation. The SPA protocol automatically includes this
combination of MOM and MCD bits.
Reading of 16 bit registers
As an example, register 223 contains 8 MOM + MCD bit pairs in 16 separate bits. The
register can be read as a regular 16 bit register revealing every bit.
Example:
>25R223I1/16:CC
<25D:1/0/0/1/1/1/1/0/0/0/1/1/0/0/1/1:CC
(I21/28) It is also possible to read the logical OR operation result of every bit pair.
Since there are 8 pairs, the OR results are 8 bits:
>25R223I21/I28:CC
<25D:1/1/1/1/0/1/0/1:CC
(I51) Reading is also possible to perform in unsigned decimal form:
>25R223I51:CC
<25D:175:CC
(I52) Or in hexadecimal form:
>25R223I52:CC
<25D:AF:CC
Reading of 32 bit registers
If the two consecutive 16 bit registers (32 bits) contain all 16 MOM + MCD bit pairs,
then the logical OR operation result (=16 bits) can be read out in one query. Assuming
the registers are 223 and 224.
(I61) In unsigned decimal form:
>25R223I61:CC
<25D:43567:CC
(I62) In hexadecimal form:
>25R223I62:CC
<25D:AA2F:CC
Vendor-specific implementation
Section 3
67