Instruction Manual

84 Communications Specification
Glossary
Deadband,
alarm
The range through which a process variable must travel from the alarm
setpoint toward the process setpoint before an alarm clears.
Derivative
control action
A control action in which the output value is proportional to the rate of
change of the error between the process variable and setpoint.
Deviation
alarm
The deviation alarm value is an absolute value that is always relative to
the setpoint. The process is in Alarm in the following cases:
Above (setpoint + deviation value)
Below (setpoint – deviation value)
Device address The communications address assigned to the controller or host software.
DLE Data Line Escape. An escape code that signals that a control code follows
it.
Double-bit
error
An error in which two bits in a packet are incorrect.
Duplex, full Communications in which each node can simultaneously transmit and
receive.
ENQ Enquiry. A control code that the software sends to the controller, asking it
to resend the last ACK or NAK.
ETX End Text. A control code that signals the end of a transmission.
Gain The parameter that users can alter through host software to set the propor-
tional control action. The gain is a unitless number that is inversely pro-
portional to the proportional band. (See also Proportional Band)
Hexadecimal
numbers
Numbers in base 16 where each digit has one of 16 possible values (0 to
F).
Integral
control action
Control action in which the output is proportional to the time integral of
the difference between the setpoint and process variable. (In other words,
the rate of change of the output is proportional to the input.)
Job A set of operating conditions (setpoints, alarms, PID constants, etc.).
Linear input Watlow Anafaze controllers have an optional linear input type that allows
you to scale raw input readings to the engineering units of your process.