Allen-Bradley 1775-S4A Operation manual

I/O Scanner Modules
Product Data
1
AllenBradley
I/O Scanner Modules
(Cat. No. 1775-S4A, -S4B)
Product Data
The I/O scanner modules provide I/O and RS-232-C communication
channels for the PLC-3 programmable controller. The two scanner modules
are:
I/O Scanner-Programmer Interface Module (cat. no.1775-S4A
I/O Scanner-Message Handling Module (cat. no. 1775-S4B)
Table Aoutlines the benefits, features, and functions for these modules.
Description

I/O Scanner Modules
Product Data
2
Table A
Benefits, Features, and Functions of the PLC3 Scanner Modules
Benefits Features Functions
High speed I/O communication with up to 2,048
inputs and 2,048 outputs per scanner
Ability to execute a faster scan for selected I/O
chassis
Ladder diagram programming or report
generation capability
Easy troubleshooting
Easy identification of PLC3 system with multiple
scanner modules
Backup system capability
Efficient production floor planning for:
GI/O communication
GPeertopeer communication
GBackup communication
Four I/O communication channels
I/O scan priority
RS232C communication channel
Status LED indicators
Thumbwheel switch
Backup connector
Terminal swing arm for extensive cabling
Communicate with I/O Adapter Modules (cat no
1771AS) in I/O chassis You can connect up to
16 I/O chassis to one I/O channel on the
scanner
Scan the I/O chassis according to a sequence
that you select
Communicates with an Industrial Terminal (cat
no 1770T4) or an RS232C compatible device
Keep you informed of the general scanner
module status and the active status of each I/O
communication channel
Distinguishes one scanner from another The
PLC3 processor requires one 1775S4A
scanner with its thumbwheel switch set to 1
Transfers control over to a backup PLC3
processor if a fault shuts down the primary
PLC3 processor
Makes connections to:
GBulletin 1771 I/O chassis up to 10,000 cable
feet away from scanner via Twinaxial Cable
(cat no 1770CD)
GCommunication channels on 1775S4A
scanners in up to 6 separate PLC3 systems
GCommunication channel on a 1775S4A
scanner in another PLC3 system

I/O Scanner Modules
Product Data
3
The following two sections of this publication explain the functional
differences between the 1775-S4A scanner and the 1775-S4B scanner.
These differences are summarized in table B. This publication also
explains the hardware components on the scanners.
Table B
Functional Differences Between 1775S4A and 1775S4B Scanners
Type of Scanner
Function Number
One
1775S4A
Another
1775S4A
1775S4B
Required for PLC3 processor operation
I/O Scanning with four I/O channels
Backup or peertopeer communication capability
Required for PLC3 backup operation
Programming interface with channel 5
Programming interface with channel 0 on PLC3
front panel
Report generation interface with channel 5
Yes
Yes
Yes
Yes
Yes1
Yes
No
No
Yes
Yes
No
Yes
No
No
No
Yes
No
No
No
No
Yes
1To Operate channel 5 on the number one 1775S4A scanner you must make I/O channel 4
inactive through the PLC3 LIST function.
You can find detailed information on these scanners in:
I/O Scanner-Programmer Interface Module User’s Manual (publication
1775-6.5.2, formerly 1775-805)
I/O Scanner-Message Handling Module User’s Manual (publication
1775-6.5.3, formerly 1775-806)
The 1775-S4A scanner is a required module for the PLC-3 programmable
controller. When you are setting up your PLC-3 system, you must insert a
1775-S4A scanner into the PLC-3 Main Processor Chassis (cat. no.
1775-A1) and set its thumbwheel switch to one. This number one
1775-S4A scanner communicates between the PLC-3 programmable
controller and:
the industrial terminal for programming interface
1771I/O chassis for I/O scanning interface
a backup PLC-3 processor that takes control over the outputs if the
primary PLC-3 processor faults
up to six PLC-3 processors for peer-to-peer communication
Using the 1775S4A Scanner

I/O Scanner Modules
Product Data
4
Programming Interface
The 1775-S4A scanner provides an RS-232-C compatible channel (channel
5) that can communicate with the industrial terminal. You can use the
industrial terminal to:
enter and monitor ladder diagram program instructions
enter and monitor data table values
force inputs and outputs
operate the PLC-3 LIST function
load and record ladder diagram programs with a Data Cartridge
Recorder (cat. no. 1770-SB) or Data Cassette Recorder (cat. no.
1770-SA)
print out ladder diagram program through channel C interface to a
printer
The number one 1775-S4A scanner supports operation of channel 0 on the
PLC-3 front panel. If you are using channel 5 on the number one
1775-S4A scanner, you must make I/O channel 4 inactive through the
PLC-3 LIST function.
Additionally, through LIST selections for the number one 1775-S4A
scanner, you can configure channel 0 on the PLC-3 front panel for
communication with the industrial terminal or an RS-232-C compatible
device.
I/O Scanning Interface
The 1775-S4A scanner provides terminals for four separate I/O
communication channels. These channels can communicate with I/O
adapter modules in I/O chassis. In scanning these I/O channels, the
1775-S4A scanner:
reads the status of output image table words from the data table and
transmits this data to update the status of the terminals on the
corresponding output module groups
receives the status from the terminals on the input module groups and
writes this data into the corresponding input image table word in the
data table
You can connect up to 16 I/O chassis on a single I/O channel. Through the
PLC-3 LIST function, you can select the sequence that the 1775-S4A
scanner scans the I/O chassis. If an I/O chassis requires a faster update
time, you can list the chassis more than once in the sequence.

I/O Scanner Modules
Product Data
5
Backup Communication
Through LIST selections for the 1775-S4A scanner, you can configure an
I/O channel for a backup communication function. In operating this
function, the I/O channel of a 1775-S4A scanner in the primary PLC-3
processor is connected to the same channel of a 1775-S4A scanner in the
backup PLC-3 processor. An input file receives data from the backup
processor. An output file sends data to the backup processor.
By cabling between the connectors labeled BACK UP on a number one
1775-S4A scanner in the primary PLC-3 processor chassis and a number
one 1775-S4A scanner in the backup PLC-3 processor chassis, you can set
up a PLC-3 backup system. In this system, if a fault disables the PLC-3
processor, the second PLC-3 processor can take control of the outputs. For
detailed information on the PLC-3 backup system, refer to the PLC-3
Programmable Controller Backup Concepts Manual (publication
1775-6.3.1, formerly 1775-803).
PeertoPeer Communication
Through LIST selections for the 1775-S4A scanner, you can configure an
I/O channel for peer-to-peer communication. In this function, you connect
the I/O channel of a 1775-S4A scanner in one PLC-3 processor to the same
channel of a 1775-S4A scanner in each of up to 6 PLC-3 processors. You
must designate one PLC-3 processor as the master of this communication
channel. The other PLC-3 processors on the channel act as slaves.
In peer-to-peer communication, the master communicates with each slave.
Through the LIST function you select a separate file in the master PLC-3
processor for each slave. This file is the source for data that transfers to the
slave PLC-3 processor(s). You also select a file in each slave PLC-3
processor that receives the data.
Peer-to-peer communication allows PLC-3 processors to exchange data
such as part counts and production status information.
You can add up to 14 additional 1775-S4A scanners for additional I/O
communication and RS-232-C capability. Each additional 1775-S4A
scanner provides four I/O communication channels and a RS-232-C
communication channel.
Additional 1775S4A Scanners

I/O Scanner Modules
Product Data
6
The 1775-S4B scanner is an optional module for the PLC-3 programmable
controller. The 1775-S4B scanner communications between the PLC-3
programmable controller and:
RS-232-C compatible devices for report generation interface
1771 I/O chassis for I/O scanning interface
Report Generation Interfaces
The 1775-S4B scanner provides an RS-232-C compatible channel (channel
5) that can communicate with data terminals, computers, printers, modems,
and other RS-232-C compatible devices. You can use these devices to
program in the report generation language available with the 1775-S4B
scanner.
By using the report generation language, you can enter and store messages
from the data terminal. You can execute these messages through the data
terminal or by using the MSG instruction in the ladder diagram program.
Report generation allows you to format text and data for display on a CRT
screen or printer. You can also display graphic presentations on a CRT
screen.
I/O Scanning Interface
The 1775-S4B scanner has terminals for four separate I/O communication
channels. You can use these channels for I/O scanning the same as the
1775-S4A scanner.
Both scanner modules have the following hardware components (figure 1):
self-test indicators
thumbwheel switch
status indicators for the I/O channels
backup connector
channel 5 connector
terminal swing arm
We describe these components in the following sections.
Using the 1775S4B Scanner
Looking at the PLC3 Scanner
Modules

I/O Scanner Modules
Product Data
7
Figure 1
Hardware Features on the PLC3 Scanner Modules
Selftest Indicators
At the top of the scanner’s front edge, LED indicators labeled PASS and
FAIL keep you informed on the general condition of the scanner. These
indicators have the following meanings:
PASS (green) FAIL (red) Meaning
On
Off
On
Off
Off
On
On
Off
Normal operation
Module fault
Powerup or system reset
PLC3 processor is
turned off
Thumbwheel Switch
The thumbwheel switch is below the self-test indicators. Setting it at a
unique number (1 to 15) enables the PLC-3 processor to distinguish one
scanner from another. That is, a 1775-S4A scanner and a 1775-S4B
scanner in the PLC-3 processor chassis can be set at the same number.
CAUTION: Do not change the thumbwheel setting on a
scanner module while PLC-3 processor power is on. Equipment
damage could result.

I/O Scanner Modules
Product Data
8
Remember, you must have a 1775-S4A scanner with its thumbwheel
switch set at 1 in the PLC-3 main processor chassis.
I/O Channel Status Indicators
Below the thumbwheel switch are four green LEDs labeled:
CH1
CH2
CH3
CH4
Each LED corresponds to one of the four I/O communication channels.
Depending on your use for the I/O communication channel, each indicator
has the following meanings:
If you are using the channel for I/O scanning with a 1775-S4A or
1775-S4B scanner:
If the LED is: Then:
On Communication between the scanner module and the I/O chassis on the
corresponding I/O channel is properly established
Flashing There is a fault on one or more of the I/O chassis on the corresponding I/O
channel
Off No I/O chassis are connected to the corresponding I/O channel or the channel is
inactive
If you are using the channel for peer to peer communication with
1775-S4A scanners:
If the LED is: Then:
On The channel is functioning properly.
Flashing The in put file that receives the data from a slave PLC3 processor is too small.
Off There is a communication problem along the channel or the channel is inactive.
If you are using the channel for backup communication with 1775-S4A
scanners:
If the LED is: Then:
The channel is functioning properly.
Flashing The input file that receives the data from the backup PLC3 processor is too
small.
Off The channel has not received data during the last 200ms or the channel is
inactive.

I/O Scanner Modules
Product Data
9
Backup Connector
Below the I/O channel status indicators is a backup connector. You can use
this connector to set up the backup system capability for switching control
over the outputs. This connector is only used for 1775-S4A scanner
number one.
Channel 5 Connector
Below the backup connector is a 25-pin D-shell connector labeled CH5.
This connector provides communication with:
an industrial terminal for ladder diagram programming and configuring
the PLC-3 system if you are using a 1775-S4A scanner
an RS-232-C compatible device for report generation if you are using a
1775-S4B scanner
To use channel 5 on 1775-S4A scanner number one, you must make I/O
channel 4 inactive through the PLC-3 LIST function.
Terminal Arm Swing
Near the bottom of the scanner module is a Terminal Swing Arm (cat. no.
1775-WA). This swing arm contains the connection for I/O communication
channels 1 to 4. Functions of these channels include:
Function Compatibility
Scanning I/O 1775S4A or 1775S4B scanners
Peer to peer communication 1775S4A scanner only
Backup communication 1775S4A scanner only
Electrostatic Discharge
Under some conditions, electrostatic discharge can degrade performance or
damage an I/O scanner module. If you observe the following precautions
you can guard against electrostatic damage.
Touch a grounded object to discharge yourself before handling the
module.
Do not touch the backplane connector or connector pins.
When not in use, keep the module in its static-shield bag.

I/O Scanner Modules
Product Data
10
Specifications
Location
GSingle slot in a PLC3 processor chassis
Functions
GI/O interface
GRS232C interface for ladder diagram
programming
GRS232C interface for report generation
I/O Capacity
G2,048 inputs and 2,048 outputs
Channels Per Scanner
G4 I/O communication
G1 RS232C communication
Communication Rate
G57.6 or 115.2 kbaud (I/O channel)
G110 baud to 19.2 kbaud
(RS232C channel)
I/O Channel Cable Length
G10,000 cable feet (max)
Nominal I/O Scan Times Per I/O Adapter
G5.5 to 6.5ms for 1 channel
G6ms for 2 channels
G6ms for 3 channels
G6.0 to 6.5ms for 4 channels
Environmental Conditions
GOperational Temperature:
0 to 60°C (32 to 140°F)
GStorage Temperature:
40 to 85°C (40 to 185°F)
GRelative Humidity:
5 to 95% (without condensation)
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As a subsidiary of Rockwell International, one of the world’s largest technology
companies — Allen-Bradley meets today’s challenges of industrial automation with over
85 years of practical plant-floor experience. More than 11,000 employees throughout the
world design, manufacture and apply a wide range of control and automation products
and supporting services to help our customers continuously improve quality, productivity
and time to market. These products and services not only control individual machines but
integrate the manufacturing process, while providing access to vital plant floor data that
can be used to support decision-making throughout the enterprise.
Publication 1775-2.5 — October, 1984
Supersedes Publication 1775-906 — May, 1982 PLC is a registered trademark of Allen-Bradley Company Copyright 1984 Allen-Bradley Company, Inc. Printed in USA