, temperature/humidity, voltage, current, or 4 to 20-mA input. The unit has an LCD and records on a 100-mm-wide strip chart using a single pen (except for the two-pen temperature/humidity model). The RD-87 has a full-function alarm that can be set to sound when measurements exceed set limits. Alarm activation can be delayed by a specified amount of time to prevent nuisance alarms caused by brief variations.