Watlow F4T User Manual

Watlow F4T • 128 • Chapter 5 Function Reference
Note:
The count is not retained through a power loss; it is set equal to the Load Value upon
power up.
Note:
The count value rolls over at the ends of its range. If the count is incremented at 9,999 it
indicates 0 and additional increments count up from there
Counter Errors
If the CNT input has an error, the count will not increment or decrement. If the RST input has
an error, the count cannot be reset. An error on one input does not impact the operation of
the other input and its associated function. Regardless of errors on the inputs, the value of
the output is set according to the count and target values and the output never has an error.
The counter function never generates or propagates an error.
Error Condition Result
- CNT has an error
- RST has no error
The count does not increment or decrement but can be reset.
- CNT has no error
- RST has an error
The count increments or decrements normally but cannot be reset.
Both inputs have
errors
The count does not increment or decrement and cannot be reset.
Current Input
This FB is found on the canvas of the FB diagram. The number of these FBs that are available
depends on the number of flex modules with current inputs installed.
Accurate current sensing requires that the controller's global AC Line Frequency be set to the
line frequency of current being measured and a current equal to or greater than 2 mA.
Note:
If an alarm is configured to monitor current as its source, the low alarm will be effective
only when the current level is equal to or greater than 2 mA. If there is no current pres-
ent, the low alarm will not be activated.
Use a current input to detect current flow in a load such as a heater and indicate a problem
if one were to occur, such as an open or short circuit.
Open and Shorted Load Circuit Detection
A Current Error can detect either an open or shorted load condition. A shorted condition
would be present if the control is calling for 0% power while current is detected as flowing
through the current transformer. Conversely, an open condition would be present when the
control is calling for power with no current flow detected through the transformer.
A Heater Error is used to determine if the load current flow is within the specified limits as
set by the user through the High Set Point and Low Set Point.

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