| Spec | Description |
|---|---|
| S1 | Block to be tested |
| S2 |
|
| Block | Type | Description |
|---|---|---|
| N | Bit | High alarm or other |
| N+1 | Bit | Low alarm, manual, or other |
| N | N+1 | |
|---|---|---|
| S2=0 | High alarm | Low alarm (non-boolean blocks only) |
| S2=1 with Station block (FC 80) | High deviation alarm | Low deviation alarm |
| S2=1 with DAANG block (FC 177) | HH or LL alarm | HHH or LLL alarm |
| S2=2 (Device drivers only) | Alarm | Manual/auto mode |