Yokogawa Wireless Temperature Transmitter YTA510 - Manual (Page 29)

<6. In-process Operation>
6-1
IM 01C50T02-01E
6. In-process Operation
6.1 Mode Transition
All function blocks have modes. All blocks have
their mode, expressed by MODE_BLK parameter.
It is a structure of four components; Target, Actual,
Permitted and Normal.
Target : Sets the operating condition of the
block.
Actual : Indicates the current operating
condition.
Permit : Indicates the operating condition that
the block is allowed to take.
Normal: Indicates the operating condition that
the block will usuall y take.
When necessary condition is satisfied, actual mode
becomes same to target. There is a chance that
actual mode says different from target by some
reason.
When the function block mode is changed to Out_
Of_Service (O/S), the function block pauses and
a block alarm is issued. When the function block
mode is changed to Manual (Man), the function
block suspends updating of output values. In this
case alone, it is possible to write a value to the
OUT parameter of the block for output. Note that no
parameter status can be changed.
6.2 Generation of Alarm
6.2.1 Indication of Alarm
When the self-diagnostics function indicates that a
device is faulty, an alarm (device alarm) is issued
from the resource block. When an error (block error)
is detected in each function block or an error in the
process value (process alarm) is detected, an alarm
is issued from each block. If an LCD indicator is
installed, the error number is displayed as AL XXX.
If two or more alarms are issued, multiple error
numbers are displayed in 2-second intervals.
For details of errors, refer to Chapter 7.
F0601.ai
Figure 6.1 Error Identification on Indicator
6.2.2 Alarms and Events
Following alarm or event can be reported by YTA as
an alert if allowed.
Analog Alerts
(Generated when a process value exceeds
threshold)
By AI Block Hi-Hi Alarm, Hi Alarm,
Low Alarm, Low-Low
Alarm
Discrets Alerts
(Generated when an abnormal condition is
detected)
By Resource Block Block Alarm, Write Alarm
By Transducer Block Block Alarm
By AI Block Block Alarm
By DI Block Block Alarm
Update Alerts
(Generated when a important (restorable)
parameter is updated)
By Resource Block Update Event
By Transducer Block Update Event
By AI Block Update Event
By AI Block Update Event
An alert has following structure: