Watlow F4T User Manual

Watlow F4T • 73 • Chapter 4 Application Examples
• The reset switch is optional. The limit can be reset using the controller’s user inter-
face. Note that it is not considered good practice to locate a reset switch in a location
so remote from the equipment that the person resetting the limit cannot be sure it is
safe to do so.
• Enter names for blocks where possible to make the application easier to understand.
• Make sure the temperature input block’s Sensor Type and other parameters are set cor-
rectly for your sensor.
• By default the limit’s Sides setting is Both. Set it to High or Low if you want to monitor
only for the process value going too high or too low, or leave it set to Both if you want
the limit to trip when the process value is either too high or too low.
• Set the limit's Low Set Point and/or High Set Point to the values at which you want to
open the limit relay’s contacts.
• Set the limit's Minimum Set Point and Maximum Set Point to the values above and below
which you do not want an operator to set the limit's Low Set Point and High Set Point.
Sensor Backup
In this example there are two thermocouples measuring the temperature of an oven. Normally
one provides feedback to a control loop that drives the heater. In the event the first thermo-
couple fails, the controller switches automatically to the second providing uninterrupted con-
trol.
Function Block Diagram

Watlow F4T Specifications

General

Inputs	Thermocouple, RTD, mA, V
Outputs	Relay, SSR, mA, V
Communication	Ethernet, Modbus RTU
Data Logging	Yes
Certifications	CE, UL, cUL, RoHS
Control Modes	PID, On/Off
Power Supply	100 to 240 VAC
Operating Temperature	0 to 50°C
Enclosure Rating	IP65
Display	4.3 in. (109 mm) color touch panel LCD
Control Loops	Up to 4