Remote-processing BASIC 52 Uživatelský manuál stáhnout pdf (Strana 21)

RPBASIC-52 PROGRAMMING GUIDE

2-2

AIN

Syntax: AIN(channel)

Where: channel = 0 to 7, is channel to convert.

Function: Converts analog input to digital number and returns a number from 0 to 4095 (0 to 1023 for the RPC-

52)

Mode: Command, Run

Use: B = AIN(N)

Cards: RPC-52, RPC-320, RPC -330. RPC-52 range is 0 to 1023 (10 bit).

DESCRIPTION

AIN returns a number corresponding to the input voltage. A number from 0 to 4095 (0 to 1023 for RPC-52)

is returned. The result is returned in under 2 ms. Input voltage may be 0-5V or ±2.5 volts, single ended or

differential. Inputs are configured for 0-5V, single ended input on power up. Use CON FIG AIN to configure

each channel's cha racteristics.

The RPC-52 does not have differential inputs or use CONFIG AIN. Refer to the RPC-52 hardware manual

for more information. The following explaination assumes a 12 bit result (0 to 4095) is returned.

A result is scaled to obtain a result representing a physical quantity. The general equation is:

variable = K * AIN(n)

where K is a scaling constant and n is the channel number. The scaling constant is determined as follows:

K = (maximum quantity - minimum quantity) / 4096

The physica l quantity can be volts, curre nt, press ure, inches, or w hatever me asurem ent you are ta king.

"maxim um quantity" is the number with its output at 5 volts while "m inimum quantity" is the num ber at 0

volts. Usually, the minimum quantity is 0.

Suppose you have a 0-200 PSI pressure transducer with a 0-5V output. To compute the constant for one

PSI/count, divide the pressure over the resolution:

K = 200/4096

K = 0.04828 = PSI change per count

To measure 0-5 volts, K = 0.001220703

CONFIG AIN

ERRORS

BAD ARGUMENT When channel expr > 7 or negative

BAD SYNTAX When channel expr left out

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Remote-processing BASIC 52 Uživatelský manuál Strana 21