Sum Check Sum; Eox : End Of System Exclusive Message - Casio PX-410R Supplementary Manual

When act = 02(BDS) or 04(HDS)
Format: 0dddddddB
For a bulk data transfer operation, the Parameter Set data to be transferred is read sequentially in 16-bit data
starting from the top address. Read values are divided into 3-byte segments as shown below, and then sent in
sequence.
The following is the conversion format, which is the same as the individual parameter 16-bit transfer detailed
above.
16-bit Memory Image
MSB: abccccccB
LSB: cdddddddB
↓
data0: 0dddddddB
data1: 0cccccccB
data2: 000000abB
Note, however, that a parameter set of 128 bytes or less can be sent using a single packet, and anything greater
than 128 bytes is divided among multiple packets.
This means that the maximum length "data" field is 128/2 × 3 = 192 bytes.
Only one parameter set can be transferred per session, and data from different parameter sets cannot be mixed
within a single packet, even when sending multiple parameter sets. Different parameter sets are always divided into
separate packets.
17.2.12

12...sum Check Sum

When act = 00(IPC), 01(IPR), 03(BDR), 05(HDR) or 7(EOD, HDA, HDJ, HDE, BSY, EOS, NOP)
Format: -
This field is always empty.
When act = 02(BDS) or 04(HDS)
Format: 0sssssssB
In this case, the "sum" field contains a value, which, when added to the total value of the "data" field, makes the
lower seven bits 0. The receiving side checks if this is true, and performs error handling (re-request, etc.) if it is
not.
17.2.13

14...EOX : End of System Exclusive Message

Format: 11110111B
(End of System Exclusive message Status = F7H)
0cccccccB 000000abB
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