QTech Data Systems DNP3 RTU - Manual (Page 18)

DATRAN XL4 RTU – Owners Manual – v1.1 June 2012
www.qtech.co.nz Page 18
Analog I/O Modes Analog I/O Modes Analog I/O Modes Analog I/O Modes
The table shows that channel pairs 1 & 2 and 3 & 4 can be configured as differential inputs, and that only channels
5 and 6 can be configured as outputs.
Analogue I/O port mode settings
Channel No Single Ended Input Differential Input Single Ended Output
1
2
3
4
5
6
Note. The voltage applied to an analog input channel should never be greater than 15V or less than 0V.
Note. Analog output channels configured as voltage output have low output impedance. Therefore, assuming a
100mA maximum output current, the minimum allowable load impedance of the attached device is 50
Ohms for 0 to 5V operation, and 100 Ohms for 0 to 10V operation.
Note. When an Analog channel is to be configured for 4 to 20mA input, configure the jumpers for 0 to 20mA
input. Then use QTech Workbench to configure the channel as 4 to 20mA.
The 6 Analog channels can each be individually configured as single ended voltage or current inputs. Channels 1
& 2 and/or 3 & 4 can be configured together to form 2 differential voltage or current input channels.
Note. For Single Ended Input channels, the input signal is referenced to ground (the ‘G’ terminal on the Analog
I/O port).
Status LEDs Status LEDs Status LEDs Status LEDs
Each analog channel has a yellow status LED to indicate the state of the channel.
Each yellow status LED shows the following channel status:
OFF Indicates that the analog input is at 0V, 0mA, or less than 4mA, depending on the mode
configured.
ON Indicates that the analog input is within the specified voltage or current range, depending on the
mode configured.
FLASHING Indicates that the analog input is at full scale or higher dependent upon the mode configured.
The terminal labelled ‘G’ is a system ground connection. The terminals labelled ‘+’ are connected to the internal
switched positive supply rail. As with any analog measurement system, care must be taken to correctly earth the
equipment to prevent earth loops. Use the ‘G’ connector on the ANALOG I/O port for all analog ground signal
return paths.
Analog I/O Signal Resolution and Accuracy Analog I/O Signal Resolution and Accuracy Analog I/O Signal Resolution and Accuracy Analog I/O Signal Resolution and Accuracy
The analog input channels are sampled by a 10 bit analog to digital converter (ADC) on the Q04 Processor. The
DATRAN XL4 software compensates the gain and offset of each analog channel to reduce measurement errors
introduced by component tolerance variations.
The analog output channels are driven from an 8 bit pulse width modulation (PWM) output from the Q04 Processor.