4 FUNCTIONS
4.7 Alert Output Function
39
4
Operation
■
Operation performed when an alert is output
Digital output values are monitored on the rate alarm alert detection cycle. When a change rate of a digital output value (from
a previous value) is equal to or more than the rate alarm upper limit value, or the rate is equal to or less than the rate alarm
lower limit value, an alert is output as follows.
• Alarm ON (1) is stored in 'Alert output flag (Rate alarm upper limit)' (Un\G38) or 'Alert output flag (Rate alarm lower limit)'
(Un\G39).
• 'Alert output signal' (Un\G69, b8) turns on.
• The ALM LED turns on.
• An alarm code is stored in 'Latest alarm code' (Un\G2). (
The conversion on a channel where an alert was output continues.
■
Operation after an alert was output
After an alert was output, if the change rate of a digital output value does not satisfy the alert output conditions due to being
smaller than the rate alarm upper limit value or being greater than the rate alarm lower limit value, Normal (0) is stored in a bit
corresponding to the channel of 'Alert output flag (Rate alarm upper limit)' (Un\G38) or 'Alert output flag (Rate alarm lower
limit)' (Un\G39).
In addition, when all 'Alert output flag (Rate alarm upper limit)' (Un\G38) and 'Alert output flag (Rate alarm lower limit)'
(Un\G39) return to Normal (0), 'Alert output signal' (Un\G69, b8) turns off and the ALM LED turns off. However, the alarm code
stored in 'Latest alarm code' (Un\G2) is not cleared. Turn off
→
on
→
off 'Error clear request' (Un\G70, b15) to clear the alarm
code.
Detection cycle
The rate alarm alert detection cycle is calculated by the following formula.
• Rate alarm alert detection cycle = Conversion cycle
×
Setting value of 'CH1 Rate alarm alert detection cycle setting'
(Un\G522)
Ex.
CH1: Current (4 to 20 mA), CH2 to 6: Conversion disabled, CH7: Pt100, CH8: When setting the input range to K and making
the following settings
• 'CH1 Rate alarm alert detection cycle setting' (Un\G522): 5 (times)
• 'CH7 Rate alarm alert detection cycle setting' (Un\G1722): 8 (times)
The CH1 rate alarm alert detection cycle is 5 ms. (1 ms
×
1 (CH)
×
5 (times))
The CH7 rate alarm alert detection cycle is 640 ms. (40 ms
×
2 (CH)
×
8 (times))
Judgment of rate alarm
The judgment of the rate alarm is judged by the following formula according to the rate alarm change rate selection and input
type setting.
■
When the rate alarm change rate selection is "rate specification"
Convert 'CH1 rate alarm upper limit value' (Un\G524) and 'CH1 rate alarm lower limit value' (Un\G526) to digit value for each
rate alarm warning detection cycle value. The following shows the conversion formula of judgment values used for the rate
alarm detection.
*1 When the input type is "current" or "voltage", set it in units of 0.1% with respect to the width (gain value - offset value) of the analog input
range.
When the input type is "RTD" or "Thermocouple", set it in units of 0.1% with respect to (maximum value - minimum value) of measured
temperature value.
Input type
Conversion formula
Case of current or voltage
Rate alarm upper limit (lower limit)
×
0.1
×
0.01
×
Maximum value of digital output value
Case of resistance temperature
detector, and thermocouple
Rate alarm upper limit value (lower limit value)
×
0.1
×
0.01
×
(upper limit value of digital output value - lower limit
value of digital output value)
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