Mitsubishi Electric MELSEC-A Manual

REVISIONS
Print Date
Aug., 1994
The manual number is given on the bottom left of the back cover.
*Manual Number
SH (NA)-351O-A
Revision
First edition

I.
INTRODUCTION
Thank youforchoosingtheMitsubishi MELSEC-A Series of GeneralPurposeProgrammable
Controllers. Please readthismanualcarefully
so thattheequipmentis used toitsoptimum. A
copy of this manual shouldbe forwarded to the end user.
,_ n .

CONTENTS
1 . GENERAL DESCRIPTION ................................................................................................. 1 . 1 . 1 . 6
1.1Whatare Computer Link Functions? .................................................................................... 1 . 2
1.2 Data Communications Using Dedicated Protocols
............................................................. 1 . 3
1.2.1 What is dedicated protocol?
...................................................................................... 1 - 3
1.2.2 Applications of dedicated protocols
......................................................................... 1 - 3
1.3 ,DataCommunications in the No-Protocol Mode
................................................................. 1 - 5
1.3.1 What is no-protocol mode? ........................................................................................ 1 - 5
1.3.2 Applications of the no-protocolmode ...................................................................... 1 - 5
1.4 Data Communications in the Bidirectional Mode ................................................................ 1 - 6
1.4.1 What is bidirectional mode? ...................................................................................... 1 - 6
1.4.2 Applications of the bidirectionalmode ..................................................................... 1 - 6
2 . SYSTEM CONFIGURATIONS .......................................................................................... 2 . 1 . 2 . 4
2.1
2.2
System Configurations that Allow Computer Link Operations and Number
of Link Stations
........................................................................................................................ 2 - 1
2.1.1When the external device (computer etc.) and the PC CPU are
inthe ratio of 1:1
......................................................................................................... 2 - 1
2.1.2 When the external device (computer etc.) and the PC CPU are
in the ratioof 1
:n ......................................................................................................... 2 - 2
2.1.3 When the external device (computers etc.) and the PC CPU are
in the ratioof 2:l
......................................................................................................... 2 - 3
System Configuration for Access to PC CPUs of Other Stations
through the MELSECNET
............................................................................. i ......................... 2 - 4
3 . PROCEDURES PRIOR TO COMPUTER LINK FUNCTION OPERATIONS
. \
DESCRIBED IN THISGUIDEBOOK .......................................................................... 3 . 1 . 3 . 11
‘-4 ....
3.1 Settings andProceduresbeforeOperations .......................................................................
3 - 1
3.1.1System configuration
...................................................................................
: .............. 3 - 2
3.1.2Functionof setting switches
......................................................................................
3 - 3
3.2Self-LoopbackTest
.................................................................................................................
3 - 4
3.3 ExternalWiring ........................................................................................................................
3 - 6
3.4 Setting the Computer ..............................................................................................................
3 - 6
3.5LoopbackTest ..........................................................................................................................
3 - 7
3.5.1 Program for loopback test (N88BASlC) ................................................................... 3 - 7
3.5.2 Loopback test procedure .......................................................................................... 3 - 10
4 . DATA COMMUNICATIONS USING DEDICATED PROTOCOLS ............................... 4 . 1 . 4 . 31
4.1 Settings Switches on theComputer Link Module AJ71 UC24 ........................................... 4 . 2
4.2 Descriptionof Indicator LEDs Related to Dedicated Protocols ........................................ 4 . 3
4.3 Dedicated Protocol Formats and Data Settings .................................................................. 4 . 4
4.3.1 Control procedure and text structure in text format
1 ............................................ 4 - 4
..... .....I._ ... ”.
..

4.4
4.5
4.6
4.7
4.3.2
Description of data settings in format 1 ................................................................... 4 - 6
4.3.3
Buffer memory allocation ........................................................................................... 4 - 9
4.3.4
I/O signals to the PC CPU ....................................................................................... 4 - 10
Sequence Program ................................................................................................................ 4 - 12 I
Reading out Data from the Device Memory inthe PC CPU ............................................ 4 - 13
4.5.1
Computer program (N88BASIC) ............................................................................. 4 - 13
4.5.2
Operation ontraining machine ................................................................................ 4 - 16
4.5.3
Outline of reading out data from device memory ................................................. 4 - 18
Writing Data into theDevice Memory in the PC CPU ...................................................... 4 - 19
4.6.1
Computer program (N88BASIC) ............................................................................. 4 - 19
4.6.2
Operation ontraining machine ................................................................................ 4 - 22
4.6.3 Outline of writing data into the device memory .................................................... 4 - 24
On-Demand Function ............................................................................................................ 4 - 25
4.7.1
What is on-demandfunction? .................................................................................. 4 - 25
4.7.2
Control procedure and text structure
4.7.3 Settings for the on-demandfunction ...................................................................... 4 - 26
'-
I
intransmission control procedure format 1 ......................................................... 4 - 25-
4.7.4 Transmitting data from the PC CPU by the on-demand function ....................... 4 - 27
5 . DATA COMMUNICATIONS USING DEDICATED PROTOCOLS ............................... 5 . 1 . 5 . 20
5.1
5.2
5.3
5.4
5.5
.. 5.6
Setting Switches onthe Computer Link Module AJ71 UC24 .............................................
5 . 2
Description of Indicator LEDs Relatedto the No-Protocol Mode ..................................... 5 . 3
Settings for theNo-Protocol Mode ........................................................................................ 5 . 4
5.3.1
Buffer memory allocation ........................................................................................... 5 . 4
5.3.2
I/O signals for PCCPU .............................................................................................. 5 . 5 F
Transmitting Data from the PC CPU ........................................................... I ......................... 5 . 9
5.5.2
Computer program (N88BASIC) .............................................................................
5 . 10
5.5.3
Operation on training machine ................................................................................ 5 . 12
5.5.4
Outline of transmitting data from the PCCPU in the no-protocol mode ........... 5 . 14- .
Receiving Data from the Computer ..................................................................................... 5 . 15 .. 4r
5.6.1 Sequence program ....................................................................................................
5 . 15 f
5.6.2 Computer program ....................................................................................................
5 . 16
5.6.3
Operation on training machine ................................................................................
5 . 18
5.6.4
Outline of receiving data from the computer in the no-protocol mode .............. 5 . 20
I/O Allocation of the Computer Link Module ........................................................................ 5 . 7
5.5.1
Sequence program ...................................................................................................... 5 . 9
r
I:
6 . COMMUNICATIONS IN THE BIDIRECTIONALMODE ............................................... 6 . 1 . 6 . 21
6.1
6.2
6.3
6.4
Setting Switches on the Computer Link Module AJ71 UC24 ............................................. 6 . 2
Description of Indicator LEDs Relatedto the Bidirectional Mode ................................... 6 . 3
6.3.1 Control procedure and text structure ....................................................................... 6 . 4
6.3.2
Data settings ................................................................................................................ 6 - 5
6.3.3 Buffer memory allocation ........................................................................................... 6 - 7
6.3.4
I/O signals to the PC CPU ......................................................................................... 6 - 8
Transmitting Data from the PC CPU ................................................................................... 6 - 10
Control Procedure and DataSettings in the Bidirectional Mode ...................................... 6 . 4

6.4.1 Sequence program .................................................................................................... 6 - 1 o
6.4.2 Computer program (N88BASIC) ............................................................................. 6 - 11
6.4.3 Operation on training machine
................................................................................ 6 - 13
6.5 Receiving Data from the Computer
..................................................................................... 6 - 16
6.5.1 Sequence program
.................................................................................................... 6 - 16
6.5.2 Program for the computer (N88BASIC)
................................................................. 6 - 17
6.5.3 Operation on training machine ................................................................................ 6 - 19
6.4.4 Outline of receiving data from the PC CPU in the bidirectional mode
.............. 6 - 15
6.5.4 Outline of receiving data from the computer in the bidirectional mode
............ 6 - 21
.I.
...
. Ill .
......--.._. /
, ..
...

, ,,,.
1. GENERALDESCRIPTION MELSEC-A
1. GENERALDESCRIPTION
This guidebookhasbeencompiled for the beginners of the computer link
module for use with the MELSEC-A series PCs
to help them understand the
following fundamentals:
what the computer link functions can do;
the usage of the computer link functions; and
the outline of the communications procedure andthe flow of data.
For the details
of the descriptions contained herein and of the multidrop link
function, refer
to the manuals listed below.Please read them andfurther
understand the functions of the computer link module.
(Reference manuals)
Computer LinWMultidrop Link Module User’s Manual
(ComputerLink Function/Printer Function)
SH-3511
For the computer link functions, refer to the followingsections in thisguide-
book:
(1) When checking computerlink functions available for dedicated
protocols
2) External wiring ........................................................... Section 3.3
3) Setting hardware ....................................................... Section 4.1
4) Datacommunications
1) Determining the system configuration ......................... Section 3.1.1
(a) Reading out data from device memory
in PC CPU
......................... ; .................................. Section 4.5
(b) Writing data into device memory in PC CPU .. i....... Section 4.6
5) On-demand function ................................................... Section 4.7
(2) When checking computer link functions available in no-protocol mode
2) External wiring ........................................................... Section 3.3
3)
Setting hardware ....................................................... Section 5.1
4) I/O allocation of the module ....................................... Section 5.4
5) Datacommunications
1) Determining the system configuration ......................... Section 3.1.1
(a) Transmitting datafrom PC CPU ............................ Section 5.5
(b) Receiving data from computer ............................... Section 5.6
(3) When checking computer link functions available in bidirectional mode
1) Determining the system configuration ......................... Section 3.1.1
2) External wiring ........................................................... Section 3.3
3) Setting hardware ....................................................... Section 6.1
4)
Datacommunications
(a) Transmittingdata from PC CPU
............................ Section 6.4
(b)Receiving data from computer ................................ Section 6.5
.............. -

1. GENERALDESCRIPTION
1.1 What areComputerLinkFunctions?
MELSEC-A
Computer link functions are intended to permit data communications between
an external device (computer, printer, etc.)and the PCCPU through the
RS-232C orRS-422 (or 485) interface of the computer link module.
The computer link functions enable the external device
to do the following:
PC
PC
0 Monitorin and dislayingthe operation
status
of t 7IF e PC C U
Collecting and analyzing data withinthe
0 Uploading and downloading sequence
Writingroductioninstructiondata to
PC
programs
the PC 8PU
Printing out data from the PC CPU
CPU Computerlink
module
v
Printer
PC
CPU Computer
link module
Bar code reader
Readingout datafrom a bar code reader ,
into the PC CPU
/
I
Data communicationsis established with a dedicated protocol or in !he
no-protocol
or bidirectional mode. 1
1-2

1. GENERALDESCRIPTION
MELSEC-A
1.2 Data CommunicationsUsing Dedicated Protocols
1.2.1 What is dedicated protocol?
Dedicated protocol is a function to read out or write data (device data etc.)
kept in the PC CPU in responseto a dedicated command ina predetermined
text format sent fromthe computer.
No special sequence program is necessary for data communications.
1.2.2 Applications of dedicated protocols
(1) Monitoring the operation status of the PC
The operation status
of a production line or machine can graphically be
monitored and checked on the computer display.
OOOQO
Parts feed line
nenoo :!;
Assembly line
OO@OO
1
s Inspectionline a
The coils are kept on during The line in operation can be
operation by the PC program. monitored on the computer
display.
(2) Collecting and analyzing data
The production output, the number ofoperation times, and other data on
a production line or machine can be shown and checked in the form of
graphs or tables on the computer display.
Ev I
Count
H
GoduE1
H
n
, ..- . ., . .

1. GENERALDESCRIPTION MELSEC-A
The quantity of products to be processedcan be set to a production line or
machine through the computer.
r
Quantity d produds ad Today'squantity of products
A to be processed
Set quantity 135281
m*
Wocr
The PC program sets the counter Write 3528 to the set quantity
tocount.thequantity
of products D5 on the counter C5 from the
processed, and production
will dis- computer.
continue on counting up to the set
number.
Uploading/Downloadingsequence programs
PC programsand parameterscan be read out into the computer.
Or, by
installing two
or more programs in the computer, a program that meets
the control purpose can be written
to the PC.
-
.. I
(Program for processing product A)
By runningthe PC with this program,
product
A can be processed.
I
Product being processed
Product name
Program
i
By writing the program corre-
sponding
to the product name
from the computer to the PC,
control can be directed.
d
?
1-4

1. GENERAL DESCRIPTION
MELSEC-A
1.3 DataCommunications in the No-Protocol Mode
1.3.1 What is no-pratocol mode?
No-protocol mode is a function to permit data communications between the
computer link module andthe external device inany data format (no specific
format, such as dedicatedprotocols, is determined on the computer link
module).
In the no-protocol made, a sequence program for transmitting
or receiving
data to/from the computer link module is required.
Data written from the sequence program into the buffer memory area of the
computer link module will be transmitted as it is tothe external device on a
request to send.
Data received from the external device, onthe other hand, will be stored into
the buffer memoryarea of thecomputer link module, and the sequence
program can read it out in the original code.
1.3.2 Applications of the wprotocol mode
Interaction between the PC CPU and the computer
Any data can be transmitted and received between the sequence pro-
gram and the computer.
Data logging
Datastored inthe PC can beprintedout on a printer through the
RS-232C
interface.
Printing out daily
production report
PC
Printer
Reading out data from a terminal
Data can beread out from
a bar code reader and used in the PC.
Bar code reader
1-5

1. GENERALDESCRIPTION MELSEC-A
1.4 DataCommunications intheBidirectional Mode
1.4.1 What is bidirectional mode?
Bidirectional mode is a function for specified data communications between
the sequence program andthe external device.
Unlike the no-protocol mode, the bidirectional mode permits data communi-
cations between the PC CPU and the external device whilesending a recep-
tion completed signal to thecommunicatingdevice.
1.4.2 Applications of the bklirectbnal made
(1) Interaction betweenthe PC CPU and the computer
Anydata can be transmitted and received between the sequence pro-
gram and the computer.
Whether the communicating device has received the data correctly can
,
be checked with responsetext.
h
(When transmitting data)
PC Cornouter
(When receiving data)
PC
-----
, . . . . . . .
esponse
CPU Computerlink
module
The computer link module processes all its response text.
1-6

2. SYSTEM CONFIGURATIONS MELSEC-A
2. SYSTEM CONFIGURATIONS
Thissectiondescribesthesystemconfigurationsforcomputerlinkopera-
tions.
2.1 System Configurations that Allow Computer Link Operations and Number of Unk Sta-
tions
Systemsusingacomputerlinkmoduleconsist
of anexternal device (com-
puter etc.) and
1 to 32 PC CPUs, two external devicesand 1 to 32 PC CPUs,
etc. Forconnectionsbetweenanexternaldeviceanda PC CPU,the
RS-
232C or RS-422/485 interface can be used.
2.1.1 When the external device (computer etc.) and the PC CPU are inthe ratio of 1 :l
Hhen the ratio is 1:1 I
Computer
RS-232C
or RS-422" (printer, CRT, etc.)
interface
RS-232C or RS-4221485 interface
CPU Computerlink
module
Available Cornputor Link Modulo Functions
Dedicated Protocol No-protocol Mode
I Bidirectional Mode
0
0 0
Fig. 2.1 System Configuration (I)
2-1

2. SYSTEM CONFIGURATIONS
MELSEC-A
2.1.2 When theexternal device (computer etc.) and the PC CPU are in the ratio of 1 :n
menthe ratio is
l-:nlp--- (n = Max. 32)
System configuration
1 The.externaldeviceisconnectedto one of thecomputerlink
modules with an RS-232C cable.
Computer
interface
RS-232Ccable
PC
(Mod.: 9 - b) PC
interface
Rs422/485 RS-4;2 cable interface
RS-422/485
interface
f
RS-422 cable
RS422f485
interface
Up to 32 stations
I System configuration 2 I The external device is connected toone of the computer link
modules with an RS-422 cable.
RS422
R54221485
Computer
PC
(Mode: 1 - 8) PC (Mod.: 1 - 8) PC (Mod.: 1 - 8)
Up to 32 stations
Available Computer Link Module Functions
Dedicated Protocol
X 00 '1
Bidirectional Mode No-protocol Mode
1 : Data communications by the on-demand function is impossible.
-~
~~p- ~~ ~ ~~~
Fig. 2.2 System Configuration (11)
2-2

2. SYSTEM CONFIGURATIONS
MELSEC-A
2.1.3 When the external device (computers etc.) and the PC CPU are inthe ratio of 2:l
Nhen
the ratio is 2:l connected to a PC CPU.)
(This system consists
of two external devices respectively
(printer, CRT, etc.)
RS-232C Computer
(printer,
CRT,
RS-232C interface
etc.)
CPU Computer link\
module
RS-422/485 interface
This system configuration uses one interface in one of dedicated
protocol formats
1 to 4, and the other in the no-protocol or bidirec-
tional mode.
Fig.
2.3 System Configuration (ill)
2-3
.. . - -_.... .... . . .
. . . ..

2. SYSTEM CONFIGURATIONS MELSEC-A
2.2 System Configuration for Access to PC CPUs of Other Stations Through the
MELSECNET
Using adedicatedprotocolenablesthecomputertocommunicatewith PC
CPUs connected via theMELSECNET.
Through a PC CPUloaded with a computer link moduleand connected to the
computer,data can be communicatedwith PC CPUs unloaded with a com-
puter link-module.
=I/
Master station (M)
PC \ PC
tu&: 1 .E) Local station 1 (Ll)
(n s 31)
PC
Local station n (Ln)
.. ..
0000
CPU J I / 1 CPU
MELSECNET (It), MELSECNET/6
All data in the device memory can be transmitted and received.
Range of PC CPUs that are communicablefrom computer
(in the case of the above system configuration)
1 ComDuter- I PC CPUs that areCommunicable 1
I Conint;d from Computer
MILlIL2IL3
Station
L1
X X
M 0
0 0 0
L1 0 0 X X
L2
0
X
X
0
L3
X 0
X
0
Fig. 2.4 System Configuration (IV)
2-4

3. PROCEDURES PRIOR TO COMPUTER LINK FUNCTION
OPERATIONS DESCRIBED
IN THtS GUIDEBOOK
MELSEC-A
3. PROCEDURESPRIORTOCOMPUTERLINKFUNCTION OPERATIONS DE-
SCRIBED
IN THIS GUIDEBOOK
3.1 SettingsandProceduresbeforeOperations
This section describes the settings of the computer link functions coveredin
this guidebook and operation procedures.
The
AJ71 UC24 is used for computer link module, and the A3UCPU for PC
CPU.
Determining the
system configuration
Setting hardware
....
(1) Setting transmission
....
control procedure
(2) Settingtransmission
....
specifications
(3) Specifyinga station
....
number
Self-loopback test
....
External wiring
....
Loopback test
....
The system consists of a computer and
a PC CPU
(1:i).
Refer to Section 3.1 .l.
Set the switches on the face ofthe
Make settings of the RS-232C interface
for computer link operations.
Refer to Sections
4, 5, and 6.
Set transmission specifications, main
channel, etc.
Refer to Section
3.1.2.
Set the stationnumber to specify which
AJ71 UC24 the computer should access
when a dedicated protocol
is used.
Refer
to Section 4.
AJ71 UC24.
Test the
AJfl UC24 unconnectedto the
computer to see
if it worksproperly.
Refer to Section 3.2.
Connect the computer
and the
AJ71 UC24 with an RS-232C cable.
Refer to Section
3.3.
Check the computer and the AJ71 UC24
to see if they communicate with each
other properly.
Refer to Section
3.5.
Selectingamode 7
Dedicated
mode mode
NO-~OIOCOI
protocol Bidirectional
. . 4
Section 4 Section 5 Section 6

3. PROCEDURES PRIOR TO COMPUTER LINK FUNCTlON
OPERATIONS
DESCRIBED INTHIS GUIDEBOOK
MELSEC-A
3.1.1 System configuration
The followingis the system configuration forcomputer link operations de-
scribed in thisguidebook.
L
1
AX42
64
[ points
x0
X3F
to
J.
7 Y7F
AJ71
UC24
32
points
4
I
I
I
I
I
I
I
I
Vacant ; Vacant
I
I
1
I
I
I
I
I
1
I
I
I
Computer
(PC9800*)
I RS-232C cable J
(X, Y80 to QF)
Y5C Y58 Y54 Y50 Y4C Y48 Y44 Y40
to to to to toto
to to
Y40 to Y5F Y5F,Y5gY57,Y5g Y4F/Y4B,Y47,Y4>
I LED display
..
Y6C Y68 Y64 Y60
Y65Y65 Y69Y63
toto
to to
Y60 to Y6F
I X77X76X75X74X73X72X71 X70
LEDx8
Y70 to Y7?
1 1
X3 F?%? X38 X34 x2-
X20 to X3F
X7X6X5 X4 X3 X2
x2toX?
Step switch x 6
x1x0
xo, x1 Pushbuttonswitch
(automatically resetting
type) x 2
PC9800 is a registeredtrademark of NEC Corp.
3-2

3. PROCEDURES PRIOR TO COMPUTER LINK FUNCTION
OPERATIONS,DESCRIBED IN THIS GUIDEBOOK
MELSEGA
3.1.2 Function of setting switches
Described below are the setting switches on the face of the AJ71UC24 and
their functions.
Station number
setting switches
set the station number
for communications us-
ing a dedicated proto-
col.
The station number can
be set between
0 and
31.
Set the switches to 0 in
1 :1 communications.
ationnum
ber 0 for
communica.
PI
Mode setting switch
This switch is
to set the mode of each
interface.
1: Communications with a dedicated
protocol in control procedure
format
1
protocol or bidirectional mode
5: Communications in the no-
F: Self-loopback test
Transmission specifications setting switches
These switches areto set the databit
length, the presence/absence
of a parity bit,
the stop bit length, sum check enableddis-
abled, etc.
SWl 1 I Mainchannel setting I OFF (RS-232C)
sw12
1 Data bit setting I OFF (7 Mts)
-1 Transmission speed setting Fl (48OOBPS)
Parity check
sw16 1 enabledldisabled
I ON (Enabled)
SW17 EvedOddparity setting ON (Even)
SW18 Stop bit setting
OFF (1 bit)
sw21
I enabled/disabled I
Sum check
OFF (Disabled)
sw22 I Write during RUN
enabledldisabled
I ON (Enabled)
SW23
I
ComputeriinWMultidrop ON link)
link selection I
I I
SW24 I Unused -
3-3

3. PROCEDURES PRIOR TO COMPUTER LINK FUNCTION
OPERATIONS
DESCRIBED IN THIS GUIDEBOOK
MELSEC-A
.I
3.2 Self-LoopbackTest
Self-loopback test is to check the AJ71 UC24to see
if it works properly when
unconnected to the computer.
The functionsfor communicationswith the PC CPU andthose of the RS-232C
or RS-422/485interfacefor transmitting and receiving data areto bechecked.
(Step 1) Settingthe mode setting switch
(Step 2) Settingthe transmission specifications setting switches
Set the mode setting switch to
"F" to select self-loopback test.
Set the transmission specifications setting switches asshown
in Section 3.1.2.
Connect the RS-232C connector cablesor RS-422/485 terminal
block cables as shown below:
(Step 3) Connectingcables
I RS232C Cable Connections
I AJ71UC24 I
cs
DSR 6
II SG i 7 1 I
~~
RS-422/465 Cablo Connections
171 Cable Connection
AJllUC24
Signal
SDA
SDB
RDA
RDB
I SG 1
t
FG
(1) Engage a connector with the above cable connections for testing to
(2) Short the terminals of the RS-422/485 connector as shown in the
the RS-232C connector.
above figure.
(Step
4) Carrying out a self-loopbacktest
1) Set the RUN/STOP key switch on the PC CPU to STOP.
2) As soon as the power to the PC CPU is turned on or the
CPU is reset, an AJ71UC24 READY signal (ready signal)
will be turned on and checkingwill automatically start.
(The
READY signal will be turned on several secondsafter
the power is turned on or the
CPU is reset.)
Checking proceeds and repeatsin thesequence of
(1) PC
CPU communications check
+ (2) RS-232C check + (3)
RS-422/485 check.
(The AJ71 UC24automatically executes it.)
3) Checkingsequence
3-4