A-B ASCll Data Transfer to theSLC 500M BASlC Module(Series B）

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Introduction

This application note demonstrates how to transfer ASCII data to an

SLC 5/02
or later processor by using a remote SLC 500 BASIC

module. An example shows how to transfer a maximum of 10

ASCII characters to an SLC 5/03 processor.

General Information

M-files cannot be accessed from a module in a remote I/O chassis.

Therefore, the BASIC module (Catalog Number 1746-BAS) is

limited to its 8 input and 8 output image words for data transfer

between itself and the SLC 5/02 or later processor. The first three

words of the I/O image are reserved for handshake bits, status, and

character count respectively. So, only 5 input and 5 output words are

available for actual data transfers. In addition, since a total of 8

words of image are used, they must be block transferred because

they do not fit in the image allocated in the Remote I/O Adapter

module (Catalog Number 1747-ASB).

To keep the BASIC programming to a minimum and the throughput

to a maximum, CALL 22 is used to transfer data from PRT1 on the

BASIC module to the SLC 5/03 processor in this case. CALL 22

operates on an interrupt basis, so the throughput of data from PRT1

to the backplane is 10 ms or less. To calculate overall throughput for

your specific system, consult your Remote I/O Adapter User Manual

(Publication 1747-6.13) and your Remote I/O Scanner User Manual

(Publication 1747-6.6).

If you also wish to transfer data from a SLC 5/02 or later processor

to a BASIC module in a remote I/O chassis, please refer to the

BASIC Language Reference Manual (Publication 1746-6.3) and

refer to the section on CALL 23.

Description of the Application Example

This application example transfers up to 10 ASCII characters to the

SLC 5/03 processor. Each data packet less than 10 characters must

be terminated with a carriage return character (13 decimal) in order

to alert the BASIC module to transfer the data to the backplane. This

termination character may actually be any unique character. If you

require a different termination character, simply replace the “13” in

line 150 of the BASIC program with the decimal equivalent of the

new termination character.

Hardware and Software Configuration Information

N7:50 to N7:52 are the control words for the BTR function. N7:53

to N7:55 are the control words for the BTW function. For this

example, the following values must be placed in these words prior to

executing the ladder logic program:

• N7:50 – Must set bit 7 of this word to make it a BTR

• N7:51 – BT length, set to decimal 8

• N7:52 – RIO address (R, G, S), set to 100 decimal

• N7:53 – Must be sure bit 7 is a 0 to make it a BTW

• N7:54 – BT length, set to decimal 1 (only one word required to

transfer handshake bits).

• N7:55 – RIO address (R, G, S), set to 100 decimal

For this application example, the Remote I/O Adapter module is

configured as a logical rack 1, starting group 0,
logical rack size.

Also, 1-slot addressing and 57.6K baud is used.