Rockwell-automation 1746-BAS BASIC LANGUAGE User Manual download pdf (Page 192)

Publication 1746-RM001A-US-P

13-2 Input Functions

CALL 22 – Transfer Data

from Port 1 or 2 to the

CPU Files

Purpose

Use CALL 22 to transfer data from the module serial ports directly to the CPU

input data file, CPU M1 file and/or an internal string within the module. During

data transfer, data is automatically transferred in 8-bit blocks from the input buffer

of the selected port to the selected SLC processor buffer and/or BASIC internal

string for storage. The transfer occurs when the specified number of characters are

detected in the input buffer of the port or the user-defined delimiter is received in

the port. The data is stored either low byte first, then high byte, or high byte first,

then low byte within the 16-bit word of the destination. Data is transferred on

word boundaries. If an odd number of bytes are to be transferred, the unused byte

contains a zero.

The byte swap selection (low byte first, then high byte, or high byte first, then low

byte) of the last CALL 22 or CALL 23 executed determines the data packing

method for all ports enabled by CALL 22.

The low byte of the first word of the destination file contains the character count

(byte count) of the data being transferred. If a delimiter is found, the byte count is

expanded to include the first occurrence of the delimiter. The second word of the

destination file contains the first two characters of data.

If an internal string is chosen, the first character of the string contains the byte

count. The second character of the internal string is a transaction number and is

incremented to inform the module that new data is in the string. The value of this

character wraps around from 255 to 0. The third character of the string contains

the first data character.

Execute CALL 22 to set up the data transfer parameters. After the CALL is

executed, the module gets data from the port and transfers it to the destination file.

Input and output image file bits (word 0, bits 8 and 9) for the slot containing the

module, are used to initiate and notify completion of the transfer. The operation is

described below:

1.1.

1. When data is available from the port, the module automatically transfers the

data into the destination buffer. This same port is checked for data at the end

of each line of BASIC code.

SLC Processor SLC Backplane BASIC or BASIC-T Module

External Device

RS-232, RS-422, or

RS-485 Network

DESTINATION

BUFFER

PORT PRT1

PORT PRT2

1 2 ... 187 188 189 190 191 192 193 194 195 196 197 ... 279 280

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Rockwell-automation 1746-BAS BASIC LANGUAGE User Manual Page 192

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