Remote-processing RPC-2350 Uživatelský manuál stáhnout pdf (Strana 43)

CHAPTER 8 ANALOG I/O

8-1

Figure 8-1 Analog connectors and jumpers

CHAPTER SYNOPSIS

 Brief description of analog input capabilities

 Acquiring analog data

 High voltage interfacing

 Converting analog readings to real world units

 Calibration

 Analog output discussion

 4-20 mA output

 Analog power supply

DESCRIPTION

ANALOG I/O CHAPTER 8

The RPC-2350 has eight single ended or four differential

analog input channels than can be interfaced to external

analog devices. These channels can be used to measure

voltages from transducers, 4-20 mA. current loops,

thermistors, etc. The converter reads a voltage and

returns a 12 bit (4096 count) num ber in under a m illi-

second. Inputs are programmable for 0 to + 5 or ±2.5

volt, single ended or differential mode.

Additionally, 2 analog outpu t channels w ith 12 bit

accuracy are optionally available. Output voltage is 0-

5V, 0-10V, or ±5V. Outputs can drive optional 4-20

mA. current loops.

Filter capacitors may be added to pads designated as

W13. This can reduce noise on analog inputs. Values

are application dependent. 0.01 mfd is a good value to

start from. Higher values ma y be used in extrem ely

noisy environments or when time be tween sam ples is

long (> 100 ms).

Input impedance is 100K ohm to ground. Inputs are

protected to ±12V. Readings on other channels are

affected when one channel is over range.

Conversion time is under 500 micr o-seconds/ channel.

AIN function is used to return a voltage while AOT

writes an output voltage.

This chapter begins with basic hook-up information, then

proceeds to initialization, data reading, and calibration.

Analog output option is discussed near the end.

Analog output 1 (AOT 1) may optionally provide

software contrast control for the LCD graphics display.

When it is used for this purpose, 4-20 Ma output or

other voltage output may not be used.

CONNECTING ANALOG I/O

Analog I/O interface via J7. The STB-20 terminal board

may be used to bring signals to terminal blocks.

The following table defines the signal pin out from

analog I/O port J7.

J7 Pin # Signal

1 CH0 input

2-16 Ground (even pins)

3 CH1 input

5 CH2 input

7 CH3 input

9 CH4 input

11 CH5 input

13 CH6 input

15 CH7 input

17 DAC 0 output

18 + 12V

19 DAC 1 output (also gr aphics contr ast)

20 -12V

1 2 ... 38 39 40 41 42 43 44 45 46 47 48 ... 82 83

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