Omron CQM1H series Operation Manual page 104

Functions
! Caution
Mean Value Processing
Function
Broken Wire Detecting Function
84
If input data is below the converted range (i.e., the input voltage of the data is
less than approximately 0.95 V or the input current of the data is less than
approximately 3.8 mA), the broken wire detection function of the Analog Input
Unit will be activated.
Conversion data
(4095) 0FFFH*
(4048) 0FD0H*
(2048) 0800H*
(0048) 0030H*
(0000) 0000H*
* "H" indicates hexadecimal.
The Analog Input Unit converts inputs 1, 2, 3, 4, 1, etc., in this order. If the input
range is 1 to 5 V or 4 to 20 mA, the Analog Input Unit may be influenced by the
previous input if the input has changed greatly. Avoid setting a range of –10 to 10
V as much as possible before using an input range of 1 to 5 V or 4 to 20 mA.
The mean value processing function of the Analog Input Unit is activated by set-
ting pin 10 of the Analog Input Unit's DIP switch to ON. If the mean value proces-
sing function is activated, all input values (inputs 1 to 4) will be averaged.
The mean value processing function enables the Analog Input Unit to convert
each input value eight times, average the values, and store the results as digital
conversion data in the input word. The contents of the word are refreshed with
intervals of approximately 72 ms.
Note By using the AVG instruction of the CPU, only particular input values can be av-
eraged or the number of averaging operations can be changed.
• The broken wire detecting function of the Analog Input Unit makes it possible to
detect and alarm the disconnection of any wire that has been connected to the
Analog Input Unit.
• The broken wire detecting function of the Analog Input Unit will work when the
input voltage and current drops to approximately 0.95 V and 3.8 mA or lower if
the Analog Input Unit is set to a range of 1 to 5 V or 4 to 20 mA.
• When the Analog Input Unit detects wire disconnection, the broken wire de-
tecting indicator (BROKEN WIRE) will be lit and the broken wire flag of the in-
put that has been disconnected will be set to 1. (Refer to 3-3-2 Adjustment)
• The broken wire detecting indicator will reset to OFF automatically when the
input returns to normal.
0 1 V (4 mA)
Approx. 0.95 V
Section 2-2
3 V (12 mA) 5 V (20 mA)
Approx. 5.4 V
Input voltage (current)