There are no dependencies between DID transmit signaling and DID receive signaling.
The following illustration shows transmit signaling for DID line interfaces:
This table summarizes the transmit signaling for DID line interfaces:
|
Bit |
Hex bitmask |
Description |
|---|---|---|
|
A bit |
0x08 |
Reverse battery polarity. 0 = Normal polarity, tip positive. 0x08 = Reverse polarity, tip negative. |
|
B bit |
0x04 |
Must be 0. |
|
C bit |
N/A |
Reserved. |
|
D bit |
N/A |
Reserved. |
The following illustration shows receive signaling for DID line interfaces:
This table summarizes the receive signaling for DID line interfaces:
|
Bit |
Hex bitmask |
Description |
|---|---|---|
|
A bit |
0x08 |
Loop current detector. 0 = No current detected. 0x08 = Current detected. |
|
B bit |
0x04 |
Same as A bit. |
|
C bit |
N/A |
Reserved. |
|
D bit |
N/A |
Reserved. |