Mitsubishi Electric MELSEC iQ-R User Manual page 59

Judgment of rate alarm
A change rate is judged with digital values per rate alarm warning detection cycle, which are calculated using values in 'CH1
Rate alarm upper limit value' (Un\G524) and 'CH1 Rate alarm lower limit value' (Un\G526).
The following shows the conversion formulas to obtain judgment values (Unit: digit) per rate alarm warning detection cycle.
/1000)  D
• D = (R
H H Max
/1000)  D
• D = (R
L L Max
Item
*1
D
H
*1
D
L
R
H
R
L
D
Max
*1 Values after the decimal point are omitted.
Ex.
The judgment value under the following conditions
• Operation mode: Normal mode (low speed: 20s/CH)
• Input range: 4 to 20mA
• A/D conversion-enabled channel: CH1
• 'CH1 Averaging process specification' (Un\G501): Sampling processing (0)
• 'CH1 Rate alarm warning detection cycle setting' (Un\G522): 5 (times)
• 'CH1 Rate alarm upper limit value' (Un\G524): 250 (25.0%)
• 'CH1 Rate alarm lower limit value' (Un\G526): 50 (5.0%)
250
D : × 32000 = 8000 (digit)
H
1000
50
D : × 32000 = 1600 (digit)
L
1000
The current value is compared with the previous value on the rate alarm warning detection cycle of 100s (Sampling cycle
20s  5). A digital value is judged if it increases 8000 digits (25.0%) or more, or judged if the increase is 1600 digits (5.0%) or
less from the previous value.
Use the following formula to calculate a change rate to be set based on the change amount of voltage and current to detect a
warning.
V/I
X
RC = × 1000
V/I - V/I
G O
Item
*2
RC
V/I
X
V/I
G
V/I
O
*2 Values after the decimal point are omitted.
Description
Upper limit value used for judgment on the rate alarm warning detection cycle (Unit: digit)
Lower limit value used for judgment on the rate alarm warning detection cycle (Unit: digit)
Rate alarm upper limit value (Unit: 0.1%)
Rate alarm lower limit value (Unit: 0.1%)
Maximum digital output value of the input range (32000)
Description
Change rate to be set (Unit: 0.1%)
Change amount of the voltage (current) to detect a warning (V (mA))
Gain voltage (current) (V (mA))
Offset voltage (current) (V (mA))
1 FUNCTIONS
1.11 Warning Output Function
1
57