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M0 File

contains four axis control structures and five setpoint profiles. 

Each axis has a variety of PID and profiling options, controlled 

by its axis control structure. Each axis also has a unique 

256-point setpoint profile. A single master setpoint profile is used 

with an “interpolate” command to ease the task of generating setpoint profiles. 

Entries in the M0 File are written by move or copy instructions in 

ladder program. Unlike changes made to the Output File, which 

are automatically detected by the module, the module must be 

explicitly instructed to download axis-control structures and 

setpoint profiles from shared memory (done by setting bits in the Output File).

M1 File 

contains four axis-status structures, four process-variable profiles, 

and a single interpolated profile. Axis-status structures are copies 

of respective axis-control structures, except that status 

information has been inserted by the module. Each 

process-variable profile provides a record of the actual position 

response to a setpoint profile. The interpolated profile is the 

result of either a linear or natural cubic-spline interpolation 

performed between the setpoints specified in the master setpoint profile. 

Unlike the Input File, which is automatically updated, the 

module must be explicitly instructed to upload axis-status 

structures, process variable profiles, and the interpolated profile 

to shared memory (done by setting bits in the Output File). 

Entries in this file are then read by move or copy instructions in ladder program.

Output File

contains 32 16-bit entries used by ladder program to command 

module operation. The Output File may also be used to supply 

process data to the module in certain situations. Entries in this 

file are updated automatically, at the end of each scan, by the 

SLC processor from the user data file but may be written at any 

time by immediate I/O instructions in the ladder program.

Input File

contains 32 16-bit entries used by ladder program to extract 

status information from the module. The Input File contains 

acknowledge bits corresponding to control bits in the Output 

File, as well as information pertaining to the profile executing on 

each analog I/O channel (step number, setpoint, analog input, 

process variable, control output, etc.) and a parameter error flag. 

The entries in this file are read automatically, once per scan, by 

the SLC processor into the user data file, but may be read at any 

time by immediate I/O instructions in ladder program.

Overview

The module performs its servo control task independently, but is dependent on the 

SLC processor for all of its configuration and run-time information. The processor 

may be also be used to supply process data or timing information over the 

backplane in certain situations (e.g. parison drop synchronization on continuous 

extrusion machines, or accumulator position in reciprocating screw machines).

The module uses a digital signal processor running a 

Proportional-Integral-Derivative (PID) algorithm to control four axes of motion. 

Four analog inputs and four analog outputs are used for process variables and 

signals, while four digital inputs and four digital outputs are used for start-of-drop 

synchronization and profile step synchronization signals, respectively. An excitation 

voltage is provided for use with linear potentiometers.

Communication with the SLC Processor

• shared memory

• control bit/status bit handshake

• micro processor

• PID control algorithm

• digital I/O

• analog I/O

Features

This 4-axis position-control module has these features:

• Open-loop or closed-loop control

• Independent and coordinated axis control

• Position- and time-based control

• Accumulator push-out control

• Zero-scale/full-scale (offset & span) calibration for position inputs

• PID with anti-windup, bumpless parameter changes, setpoint weighting, and 

limited high-frequency derivative gain.

• Profile interpolation (linear or cubic spline) between setpoints

• Converging/diverging tooling (direct/reverse acting control)

• Three hold values per axis: manual position, purge, or die gap

• Independent profile scale and offset adjustments 

• Automatic parison weight adjustment

• Setpoint marking

Shared memory

From the ladder programmer’s perspective, communication with the module is via 

five data files located in shared memory on the module:

Config(G) File

contains information regarding the operational mode and feature 

settings of the module. You specify the contents of this file with 

the ladder logic programming utility (RSLogix500). Entries in the 

file are static and read-only from the module’s perspective (e.g. 

time vs. position based operation). This file is automatically 

downloaded to the module when you switch the SLC processor to Run mode. 

The development software enables you to program the module from a 

personal computer connected to either the module’s DH485 or PRT1 

ports. The software allows direct access to the module through 

terminal emulation over an RS-232/423 or DH485 network.

Refer to the BASIC Development Software Programming Manual, 

publication 1746-PM001, for additional information on the software.

Typical Configurations

The typical configuration of the SLC system that incorporates your 

BASIC or BASIC-T module depends on whether the module is:

• integrated with a SLC 500 fixed or modular controller.

• programmed directly with an ASCII terminal or programmed 

using a personal computer with the BASIC development 

software, 1747-PBASE.

• communicating with a DH485 network or with an external 

source through a modem using DF1 protocol.

Module Integration

The module is a single-slot module that is inserted into a slot in the 

expansion chassis of your SLC 500 fixed controller or an open slot in 

the 1746 I/O chassis of your SLC 500 modular controller. The module 

may be inserted in any slot of the 1746 I/O chassis except the first slot 

of the first chassis, which is reserved for the SLC modular processor. 

Typical SLC fixed and modular configurations are shown in the 

following figures.

The BASIC development software provides the user with a structured 

and efficient means to create BASIC programs for the module. This 

software is loaded into a an MS-DOS compatible personal computer. It 

uses the personal computer to facilitate editing, compiling 

(translating), uploading, and downloading of BASIC programs. 

The BASIC development software has a menu-driven, window-type 

environment that offers: 

• pull-down menus to access all editor functions.

• function key access to frequently used functions.

• multiple window editing.

• cut and paste support between windows.

• search and replace support.

• search between files support.

• built-in calculator that can paste results into your program.

• ASCII look-up table.

• line draw editor to create operator interface images without having to enter ASCII characters.

• keystroke macros.

• undo and redo functions.

• extensive help messages for each menu, menu option, and for keywords embedded in the menu text.

• capability to create user-defined macro libraries.

• sophisticated debug tools including watch windows, single-step 

operation, and go to cursor breakpoint operation.

• syntax checked translations to native BASIC to reduce debug time.

• BASIC translator that steps through the BASIC program and identifies errors.

• ASCII terminal mode.

• hex file transfer support.

Software Features

The module provides the following software features.

• BASIC programming with the Intel BASIC-52 language and enhancements

• SLC 500 backplane data read and write support including image 

table transfers and M0 and M1 file transfers

• Execution of programs from memory modules

• String manipulation support

• DH485 network support

• DF1 protocol support

• Full set of trigonometric function instructions

• Floating point calculations and conversion

• Extensive call libraries

Module Communication Ports

There are three communication ports on the front of the module. The 

location, name, and pin numbers of these ports are listed on the 

inside of the module door. 

They are:

• PRT1 – Used to interface the module with user devices. This port 

is a serial port that accommodates RS-232/423, RS-422, and 

RS-485 communication modes. Port PRT1 is capable of operating 

full-duplex at 300, 600, 1200, 2400, 4800, 9600, and 19200 Kbps. 

The default settings are 1200 Kbps, RS-232/423 communications.

• PRT2 – Used to interface the module with user devices or a 

modem using DF1 protocol. This port is a serial port that 

accommodates RS-232/423, RS-422, and RS-485 communication 

modes. Port PRT2 is capable of operating full-duplex at 300, 600, 

1200, 2400, 4800, 9600, and 19200 Kbps.

• DH485 – Used to interface the module with the DH485 network. 

This port is not isolated and cannot directly drive the DH485 network. 

You must use a 1747-AIC link coupler to link port DH485 with the DH485 network.

BASIC and BASIC-T Modules

The modules are single-slot modules that reside in a SLC 500 fixed or modular controller chassis.

Use the module as:

• a foreign device interface.

• an operator interface.

Hardware Features

The module provides the following hardware features.

• 24 KB of battery backed RAM for storage of user programs and data

• Capacitive backup of RAM during battery change

• Socket for a standard 1747-M1, M2, M3, or M4 memory module 

(1746-BAS module) for nonvolatile storage of user programs

• Socket for a 1771-DBMEM1 or -DBMEM2 memory module 

(1746-BAS-T module) for nonvolatile storage of user programs

• Battery-backed, 24-hour clock/calendar

• Free-running clock with 5 ms resolution

• Two isolated 9-pin D-shell serial ports (PRT1 and PRT2) that 

provide RS-232/423, RS-422, and RS-485 communication with I/O devices

• One PRT2 port provides DF1 full-duplex or half-duplex slave 

protocol for SCADA applications

• One RJ-45 port (DH485) that provides communication over the DH485 network

• Multiple LED indicators for operator interface

• SLC 500 backplane interface

Overview

The module and the development software provide the following benefits.

• Easy data collection from user devices

• Integrated program debugging environment

• Operator interface capabilities

• Flexible program and data storage options

• High-level math

• Clock/calendar

• High-level programming environment

• Extensive online help system

• Easy access to editor functions through user interface

• Advanced text editor windows

TIP

The 1746-BAS-T module is a higher-speed version of 

the 1746-BAS module with identical hardware 

features. The modules can be interchanged, except 

that the 1746-BAS-T module uses different (optional) 

memory modules. Due to the high speed of the 

1746-BAS-T module, existing programs written for 

the 1746-BAS module may require adjustment for 

identical operation using the faster 1746-BAS-T module.

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.