7-2
Section
Analog Output Units
125
4 to 20 mA
The hexadecimal values 0000 to 1770 (0 to 6000) correspond to an analog
current range of 4 to 20 mA. The entire output range is 3.2 to 20.8 mA.
Converted data
Hexadecimal
(Decimal)
Current
20.8
mA
20 mA
4 mA
3.2 mA
0 mA
FED4
(--300)
1770
(6000)
189C
(6300)
8000
0000 (0)
7FFF
The Configurator or pins 8 and 9 of the DIP switch can be used to determine the
status of the outputs after a communications error occurs in CompoBus/D or I/O
Unit interface communications. The following settings are possible:
•
Hold (maintain previous output status)
•
Clear at minimum (clear at the lower limit of the output signal range)
•
Clear at maximum (clear at the upper limit of the output signal range)
•
Clear at 0 V (for --10 to 10 V only)
When the clear at minimum, clear at maximum, or clear at 0 V setting is used, the
output data will be as shown in the following table.
Output signal
range
Clear at minimum
Clear at
maximum
Clear at 0 V
0 to 5 V
--0.25 V
5.25 V
--0.25 V
1 to 5 V
0.8 V
5.2 V
0.8 V
0 to 10 V
--0.5 V
10.5 V
--0.5 V
--10 to 10 V
--11 V
11 V
0 V
4 to 20 mA
3.2 mA
20.8 mA
3.2 mA
Output the converted data to the Master as shown in the following diagram.
Bit
First word
First word + 1
First word + 2
First word + 3
Output 0 data
Output 1 data
Output 2 data
Output 3 data
When a negative voltage is to be output, specify the conversion data as the two’s
complement. To obtain a two’s complement from an absolute value, the NEG
instruction is useful.
The conversion data is refreshed every 4 ms for all 4 points.
Output Status after
Communications Error
Converted Data
Conversion Time