From the AltaCore-1553 manual:
https://www.altadt.com/ReleaseDownloads/AltaCore-1553%20Spec-Users%20Manual.pdf
Differential Discrete Output Register: W: 0x00000084
This word is used to control the output state of the differential RS485 discretes.
Bits 15-0: Output Control: W
Discrete outputs can be driven high (Active) by setting the corresponding bit in this register to a one. Bit0=Discrete1, Bit1= Discrete2, etc.
The corresponding transmit enable bit must be set before this bit is valid. Bit0=Discrete1, Bit1= Discrete2, etc.
Bits 31-16: Output Enable: W
These bits control the output enables of the uni-directional differential RS485. If a given bit is set to a one, the discrete output is enabled (transmit mode).
If a given bit is set to a zero, the discrete output is disabled (receive mode). Bit16=Discrete1, Bit17= Discrete2, etc.
To control discrete outputs, you would first perform a masked-write to the appropriate bits in the DifferentialDiscrete Output Register->Output Enable bits,
then perform the same type of masked-write to set/clear the output in the Differential Discrete Output Register->Output Control bits.
Note that the functionality is the same for the ARINC product line, but the offset to the Differential Discrete Output Register is different.
Refer to the AltaCore-ARINC Spec User Manual:
https://www.altadt.com/ReleaseDownloads/AltaCore-ARINC%20Spec-Users%20Manual.pdf
