Omron CRT1 - 10-2008, Operation Manual

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Analog Input Slave Units Section 6-4
■
Input Range: 4 to 20 mA
The current range 4 to 20 mA corresponds to 0000 to 1770 hex (0 to 6,000).
The convertible data range is FED4 to 189C hex (
–
300 to 6,300). If the input
current is below the input range (input current less than 3.04 mA), a discon-
nection is detected and the data is set to 7FFF hex.
AD Conversion Data
Negative AD conversion data is expressed as two’s complements. The NEG
instruction (two’s complement conversion) can be used to obtain the absolute
value of the two’s complement.
Conversion Speed
The AD conversion data for 4 input points is refreshed every 3.82 ms max.,
although the conversion speed will vary depending on the functions and num-
ber of AD conversion points being used. Refer to
6-4-3 Calculating the Con-
version Cycle for details.
189C (6300)
1770 (6000)
FED4 (
−
300)
0000 (0)
4 mA
3.2 mA
20 mA 20.8 mA
7FFF
3.04 mA
(Disconnection detected below 3.04 mA.)
Conversion data
Hexadecimal (decimal)
Current
Clamped above
20.8 mA.
3 0 2 1 4 6 5 7 8 10 9 11 12 14 13 Bit 15
Input 0 AD conversion data
Input 1 AD conversion data
Input 2 AD conversion data
Input 3 AD conversion data
First word + 0
First word + 1
First word + 2
First word + 3