RKC INSTRUMENT Z-TIO-G, Instruction Manual

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9. COMMUNICATION DATA DESCRIPTION
IMS01T28-E4
9-20
Control loop break alarm (LBA) time
RKC communication
identifier A5
Modbus
register address ch1: 0086H (134)
ch2: 0087H (135)
The LBA time sets the time required for the LBA function to determine there is a loop failure. When the
LBA is output (under alarm status), the LBA function still monitors the Measured value (PV) variation at
an interval of the LBA time.
Attribute:
R/W
Digits:
7 digits
Number of data:
2 (Data of each channel)
Data range:
0 to 7200 seconds (0: Unused)
Related parameters:
LBA deadband (P. 9-21), Event 4 type (P. 9-52)
Factory set value:
480
Function:
The Control loop break alarm (LBA) function is used to detect a load (heater) break
or a failure in the external actuator (power controller, magnet relay, etc.), or a failure
in the control loop caused by an input (sensor) break.
The LBA function is activated when control output reaches 0 % (low limit with
output limit function) or 100 % (high limit with output limit function). LBA
monitors variation of the Measured value (PV) for the length of LBA time. When
the LBA time has elapsed and the PV is still within the alarm determination range,
the LBA will be ON.
[Alarm action]
LBA determination range: RTD input: 2

C (fixed)
Voltage input: 0.2 % of input span (fixed)

Heat control
When the output reaches 0 %
(low limit with output limit function)
When the output exceeds 100 %
(high limit with output limit function)
For
reverse
action When the LBA time has passed and the PV has
not fallen below the alarm determination range,
the alarm will be turned on. When the LBA time has passed and the PV has
not risen beyond the alarm determination range,
the alarm will be turned on.
For
direct
action When the LBA time has passed and the PV has
not risen beyond the alarm determination range,
the alarm will be turned on. When the LBA time has passed and the PV has
not risen beyond the alarm determination range,
the alarm will be turned on.
If the Autotuning function is used, the LBA time is automatically set twice as large as the Integral
time. The LBA setting time will not be changed even if the Integral time is changed.
If the LBA function detects an error occurring in the control loop, but cannot specify the location,
a check of the control loop in order. The LBA function does not detect a location which causes
alarm status. If LBA alarm is ON, check each device or wiring of the control loop.
When AT function is activated, the controller is in STOP mode, the LBA time is set to 0 or the
LBA function is not assigned to Event 4, the LBA function is not activated.
If the LBA setting time does not match the controlled object requirements, the LBA setting time
should be lengthened. If setting time is not correct, the LBA will malfunction by turning on or off
at inappropriate time or not turning on at all.
While the LBA is ON (under alarm status), the following conditions cancel the alarm status and
LBA will be OFF.

The Measured value (PV) rises beyond (or falls below) the LBA determination range within the
LBA time.

The Measured value (PV) enters within the LBA deadband.