BECKHOFF ET1100 - Manual (Page 93)

PDI description
Slave Controller – ET1100 Hardware Description III-79
6.5.5 µController connection using Transfer Size signals (SIZ)
In case the µController does not provide Byte High Enable, and Transfer Size signals (SIZ or TSIZ)
are available, they can be used to distinguish between 8 and 16 bit accesses together with ADR[0]. An
exclusive-or combination of ADR[0] and SIZ[0] is equivalent to BHE. This combination can be
configured with Byte access mode set to one (Transfer Size mode).
Table 74: Byte Select vs. ADR[0] and BHE
µController EtherCAT device Access
ADR[0] SIZ[1:0] ADR[0] xor
SIZ[0] ADR[0] BHE
(act. low)
0 10 0 0 0 16 bit access (low and high byte)
0 01 1 0 1 8 bit access (low byte, even
address)
1 01 0 1 0 8 bit access (high byte, odd
address)
0 00 0 0 0 32 bit access (splitted in two 16
bit accesses)