Mitsubishi Electric MELSEC iQ-R Series Programming Manual page 305

■Three-position (on/off) control
This function block performs three-position (on/off) control in accordance with a manipulated value.
Condition
MV  75 (%)
25 (%)  MV < 75 (%)
MV < 25 (%)
MVB1, MVB2: Three-position (on/off) output, MV: MV output
• Set an integral multiple of the execution cycle (T) as a control cycle (CT).
■Engineering value conversion
This function block converts the setting value (%) from the primary loop in the CAS or CSV mode into an engineering value.
RH-RL
SV= ×Setting value (%) from primary loop + RL
100
RH: Engineering value high limit, RL: Engineering value low limit, SV: Setting value
■Inverse engineering value conversion
This function block converts the setting value (SV) of an engineering value into a setting value (SV) in percentage (%).
100
SV(%)= ×(SV-RL)
RH-RL
RH: Engineering value high limit, RL: Engineering value low limit, SV: Setting value
■Tracking processing
The following table shows whether tracking processing to the input variable CASIN_T is performed or not.
Condition
Tracking Flag (TRK)
1
0
■Loop stop processing
When the stop alarm (SPA) of the alarm (ALM) is TRUE, this function block performs the following processing.
• Outputs (MVP) are held.
• The control mode is automatically switched to MANUAL.
■Processing operation
: Performed, : Not performed
Control mode Processing operation
MV correction
MAN, CMV, AUT 

CAS, CSV
*1 Tracking is performed when the tracking flag (TRK) is 1.
Three-position (on/off) output
MVB1
TRUE
FALSE
FALSE
Setting Value (SV) Used (SVPTN_B0)
FALSE
TRUE
FALSE or TRUE
Three-position (on/
off) control


10.22 3 position ON/OFF Control (Enable Tracking for primary loop) (M+P_ONF3_T)
MVB2
FALSE
FALSE
TRUE
Result
The input variable CASIN_T is tracked.
The input variable CASIN_T is not tracked.
Engineering value Inverse
conversion engineering value
conversion
 
 
10 LOOP CONTROL OPERATION
10
Tracking
*1


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