Yokogawa RotaMASS 3-Series - Manual (Page 155)

APPENdIX 5. PId BLOCK
a-55
IM 01R04B05-00E-E 3rd edition July 30, 2010 -00 all Rights Reserved. Copyright © 2005, Rota Yokogawa
* the modes to which a PID block can transfer
are limited to those set in MoDE_BLK.permit-
ted, and the priority levels of modes are as
shown below. In fact, if normal shed, normal
return is set for SHED_oPt, detection of a
computer failure causes MoDE_BLK.actual to
change to CaS, auto, or Man, whichever is
set in MoDE_BLK.permitted and has the low-
est priority level.
Man Higher priority level
auto
CaS
RCaS
Rout
Lower priorty level
** only if auto is included in MoDE_BLK.permit-
ted. If the block upstream of the PID block in
question is a control block, mode transitions
of the PID block to CaS occur in the following
sequence due to initialization of the cascade
connection: RCaS or Rout ∅ auto ∅ CaS.
A5.18 Alarms
there are two kinds of alarms generated by a PID
block: block and process alarms.
A5.18.1 Block Alarm (BLOCK_ALM)
the block alarm BLoCK_aLM is generated upon
occurrence of either of the following errors (values
set in BLoCK_ERR) and notifies the content of
BLoCK_ERR.
Value of
BLoCK_ERR
Condition
In.status of the PID block is either of the
following:
• Bad-Device Failure
• Bad-Sensor Failure
MoDE_BLK.target of the PID block is o/S.
Input Failure
out of Service
ta0511.EPS
A5.18.2 Process Alarms
there are six types of process alarms. only one
process alarm can be generated at the same
time, and the process alarm having the highest
priority level from among those occurring at the
same time is generated. the priority level is set
for each process alarm type.
Parameter
Containing
Priority
Level Setting
Cause of occurrence
Process
alarm
occurs when the PV increases
above the HI_HI_LIM value.
occurs when the PV increases
above HI_LIM value.
occurs when the PV decreases
below the Lo_LIM value.
occurs when the PV decreases
below the Lo_Lo_LIM value.
occurs when the value of
[PV - SP] increases above the
DV_HI_LIM value.
occurs when the value of
[PV - SP] decreases below the
DV_Lo_LIM value.
HI_HI_PRI
HI_PRI
Lo_PRI
Lo_Lo_LIM
DV_HI_PRI
DV_Lo_PRI
HI_HI_aLM
HI_aLM
Lo_aLM
Lo_Lo_aLM
DV_HI_aLM
DV_Lo_aLM
ta0512.EPS
A5.19 Example of Block
Connections
PID
BKCaL_In out
In
ao
BKCaL_out
CaS_In
aI
out
Fa0506.EPS