Common Database patterns

Pull Alarm Status w/o Data

This is useful to bring alarm status in without affecting the value stored in a record. In the following example the alarm status of $(P):set is fetched by $(P):rbv when it is processed, but the value is read from a different record.

record(bo, "$(P):set") {
    field(OSEV, "MAJOR")
    field(FLNK, "$(P):rbv")
}
record(bi, "$(P):rbv") {
    field(SDIS, "$(P):set NPP MS")
    field(DISV, "-1")
    field(INP , "$(P):some:other:record")
}

Combined Setting and Readback

Use when a single PV is desired. Could be used to show the results of rounding in a float to fixed precision conversion.

In the following example the value read from a ‘bi’ is inverted so that the associated ‘bo’ acts as a toggle.

record(bi, "$(P):rbv") {
    field(DTYP, "...")
    field(INP , "...")
    field(PINI, "YES")
    field(FLNK, "$(P):inv")
}
record(calcout, "$(P):inv")
    field(CALC, "!A")
    field(INPA, "$(P):rbv")
    field(OUT , "$(P) NPP")
}
record(bo, "$(P)") {
    field(DTYP, "...")
    field(OUT , "...")
    field(FLNK, "$(P):rbv")
}

The important point is the NPP modifier on output link of the ‘calcout’ record. This updates the VAL field of the ‘bo’ record (and posts monitors) without processing it.