Every effort has been made to ensure that the information in this document is complete,
accurate, and up-to-date. The manufacturer assumes no responsibility for the results of
errors beyond its control. The manufacturer also cannot guarantee that changes in software
and equipment made by other manufacturers and referred to in this guide will not affect
the applicability of the inform a t ion in i t. Mention of software products manufactured by
other companies does not necessarily constitute endorsement by the manufacturer.
While all reasonable efforts have been made to make this document as accurate and helpful
as possible, we make no warranty of any kind, expressed or implied, as t o the accuracy or
completeness of the information contained herein.
The most up-to-date drivers and manuals are available from the web site:
As an ENERGY STAR Program Participant, the manufacturer has determined
that this product meets the ENERGY STAR guidelines for energy efficiency.
This product complies with the requirements of the Council Directives 2004/
108/EC (EMC), 2006/95/EC (LVD) and 2009/125/EC (ErP) as amended where
applicable on the approximation of the laws of the member states relating to
electromagnetic compatibility, low voltage and energy related product.
This product complies with EN55022 Class B. However, when fitted with the
optional network interface card or optional cut-sheet feeder, compliance to
EN55022 is Class A. In a domestic environment this configuration may cause
radio interference, in which case the user may be required to take adequate
control measures.
The following cables were used to evaluate this product to achieve EMC directive
2004/108/EC compliance and configurations other than this may affect that compliance.
CABLE TYPELENGTH
(METRE)
Power1.8
USB5.0
Serial2.1
Parallel2.0
CORESHIELD
✘✘
✘✔
✘✔
✘✔
LAN5.0
✘✘
Preface > 2
M
ANUFACTURER
Oki Data Corporation,
4-11-22 Shibaura, Minato-ku,
Tokyo 108-8551,
Japan
I
MPORTER TO THE
Oki Europe Limited (trading as Oki Printing Solutions)
Blays House
Wick Road
Egham
Surrey, TW20 0HJ
United Kingdom
For all sales, support and general enquiries contact your local distributor.
NOTE
A note provides additional information to supplement the main text.
CAUTION!
A caution provides additional information which, if ignored, may
result in equipment malfunction or damage.
WARNING!
A warning provides additional information which, if ignored, may
result in a risk of personal injury.
For the protection of your product, and in order to ensure that you benefit from its full
functionality, this model has been designed to operate only with genuine original ribbon
cartridges. Any other ribbon cartridge may not operate at all, even if it is described as
“compatible”, and if it does work, your product's performance and print quality may be
degraded.
Use of non-genuine products may invalidate your warranty.
Specifications subject to change without notice. All trademarks acknowledged.
Notes, cautions and warnings > 7
A
BOUT THIS GUIDE
NOTE
Images used in this manual may include optional features that your printer
does not have installed.
If required, you may wish to refer for basic information to the User’s Guide
which is stored on the manuals CD.
This manual is your Technical Reference guide (check the web site,
www.okiprintingsolutions.com, for the most up-to-date version) for your printer and forms
part of the overall user support listed below:
>Installation Safety booklet: provides information as to safe use of the printer.
This is a paper document that is packaged with the printer and should be read before
setting up your printer.
>Set-up guide: to describe how to unpack and set up your printer.
This is a paper document that is packaged with the printer.
>This Technical Reference Guide: to provide detailed technical information for
programmers and more technical users.
This is an electronic document available on the support web site.
>User’s Guide: to help you to become familiar with your printer and make the best
use of its many features. Also included are guidelines for troubleshooting and
maintenance to ensure that it performs at its best. Additionally, information is
provided for adding optional accessories as your printing needs evolve.
This is an electronic document stored on the manuals CD.
>Network Guide: to provide detailed technical information for network
administrators to configure the optional accessory network interface.
This is an electronic document stored on the CD that accompanies the network
interface card optional accessory.
>Installation Guides: accompany consumable items and optional accessories to
describe how to install them.
These are paper documents that are packaged with the consumables and optional
accessories.
>Online Help: online information accessible from the printer driver and utility
software.
O
NLINE USAGE
This guide is intended to be read on screen using an Adobe Acrobat Reader. Use the
navigation and viewing tools provided in Acrobat.
You can access specific information in two ways:
>In the list of bookmarks down the left hand side of your screen, click on the topic of
interest to jump to the required topic. (If the bookmarks are not available, use the
“Contents” on page 4.)
>In the list of bookmarks, click on Index to jump to the Index. (If the bookmarks are
not available, use the “Contents” on page 4.) Find the term of interest in the
alphabetically arranged index and click on the associated page number to jump to
the page containing the term.
About this guide > 8
P
RINTING PAGES
The whole manual, individual pages, or sections may be printed. The procedure is:
1.From the toolbar, select File, then Print (or press the Ctrl + P keys).
2.Choose which pages you wish to print:
(a)All pages, (1), for the entire manual.
(b)Current page, (2), for the page at which you are looking.
1
2
3
(c)Pages from and to, (3), for the range of pages you specify by entering their
page numbers.
3.Click OK.
About this guide > 9
I
NTRODUCTION
This printer series is designed to provide highly reliable letter quality printing and high
resolution graphics for the desktop/office printing environment. It combines state-of-theart, 9-pin (ML5720/ML5721) and 24-pin (ML5790/ML5791), serial impact dot matrix
printing technology with advanced materials and superior construction to provide high
performance and versatility in a desktop sized unit. Careful attention to ergonomics and
application needs provides user friendly operation for operators of varying technical
capabilities.
F
EATURES
The features include:
>OKI smart Paper Handling
>9-pin(ML5720/ML5721) and 24-pin(ML5790/ML5791) double arrangement operator
replaceable printhead
>Direct access control panel
>Structured direct access menu for easy set up
>Printhead life: 400M characters (average) in 10 CPI Utility mode at normal 25%
> Automatic sheet loading
> Short paper tear-off available by menu selection or TEAR button operation
> Auto-loading for single sheet and continuous paper
> Auto park feature
Introduction > 10
>Paper copies
ML5720/ML5721ML5790/ML5791
9 - 11 lb, 6 part (with Rear/Front
Push feed)
9 – 11 lb, 7 part (with Pull tractor
Front/Bottom Pull feed)
(See note)
NOTE
Depending on the paper route and media type, printout may appear light on
the last paper part. It is recommended to use High Copy mode when the print
appears light.
> Standard IEEE1284 parallel interface
> USB interface
> Optional RS-232C serial interface
> Optional Network interface card
9 - 11 lb, 6 part (See Note)
>ML5720/ML5721:Quiet operation at 55 dB(A) in quiet mode and 57 dB(A) in normal
mode
>ML5790/ML5791:Quiet Operation at 52 dB(A) in quiet mode and 57 dB(A) in normal
mode.
>128 kbytes max. receive buffer
>
ML5720/ML5721: Line feed resolution at 1/6 inch, 1/8 inch, n/72 inch,
n/144 inch, n/216 simulated by n/288 inch
ML5790/ML5791: Line feed resolution at 1/6 inch, 1/8 inch, n/60 inch,
n/72 inch, n/180 inch, n/216 inch, n/360 inch.
>Agency approved: GS,CE
>Barcode data printing
>Postnet bar code data printing
Introduction > 11
S
TANDARD CONFIGURATION
This printer seriesconsists of the following components:
>Printer mechanism
>Power supply unit
>Control board (including an IEEE1284 parallel interface and USB port)
>Operator panel board
>Acoustic covers
>Tractor feed unit
O
PTIONS
>RS-232C Serial Interface Board
NOTE
Ensure that the RS-232C Serial Interface board’s communication rate is up to
19.2 K BPS. RS-232C with a lower K BPS cannot be used for this printer.
>LAN7120E3 100BASE-TX/10BASE-T Network Board
>Tractor unit (Push and Pull)
>Cut-sheet feeder (Single-bin only)
>Roll paper stand (ML5720/ML5790)
Introduction > 12
I
DENTIFYING COMPONENT PARTS
The main parts of your printer are identified and briefly explained below.
F
RONT VIEW
10
9
8
7
1
9
6
2
5
3
4
1.Power Switch: to turn the printer power ON/OFF.
2.Operator Panel: contains buttons and indicators (LEDs) (described in detail later)
that allow you to operate the printer.
3.Front Feed Paper Tray: to feed the cut sheet from the fron t .
4.Front Cover: open to fit the front feed paper tray or to fit the tractor.
5.Platen Knob.
6.Paper Type Lever: set according to the type of paper feed - front feed (cut sheet),
continuous rear feed, continuous front feed or continuous bottom pull.
7.Pull-up Guide Assembly support.
8.Top Feed Paper Tray: raise to feed cut sheet paper from the top.
9.Paper Guide: can be adjusted as required to locate the left edge of cut sheet paper.
10.Top Cover: open and close for access, for example when changing a ribbon
cartridge. Keep closed for noise reduction.
Introduction > 13
I
NTERNAL VIEW
11
12
13
14
11.Paper Thickness Lever: set according to the thickness of the paper.
12.Ribbon Cartridge: holds the printer ribbon.
13.Print Head: prints the character on the paper.
14.Pull-up Guide assembly: remove whe n using Pull tractor and optional Cut-sheet
feeder.
R
EAR VIEW
18
16
15
19
17
20
15.USB connector: connect to USB interface cable.
16.Parallel connector: connect to parallel interface cable.
17.Optional Serial/Network connector: connect to serial or network.
18.Optional CSF/RPS connector: connect to cut-sheet feeder or roll paper stand.
19.Ventilator
20.A/C Input: connect to printer power cable.
Introduction > 14
I
NTERFACE SPECIFICATIONS
IEEE1284
C
ONNECTORS AND CABLE
PARALLEL INTERFACE SPECIFICATIONS
Connectors
Printer side:36-pin receptacle 57RE-40360-830B-D29BF (DDk Ltd.) or equivalent
Cable side:36-pin plug 57FE-30360 (DDK Ltd.) or equivalent, or 57F-36H-3R straight
type with a metal hood (DDK Ltd.) or equivalent.
Cable
Use a cable less than 1.8 m in total length.
(A shielded cable is required and use of twisted-pair wires is recommended for noise
prevention.)
P
ARALLEL INTERFACE SIGNALS
Pin No.SignalDirection
1STROBETo printer Samples input data when changing from low
2DATA BIT 1To printer Input data: High level indicates “1” and low
3DATA BIT 2
4DATA BIT 3
5DATA BIT 4
6DATA BIT 5
7DATA BIT 6
8DATA BIT 7
9DATA BIT 8
10 ACKNOWLEDGE From printer Indicates character input completion, or func-
11 BUSYFrom printer
12 PAPER ENDFrom printer High level indicates paper end.AckDataReq
13 SELECTFrom printer High level indicates select (on line) condition. Xflag
14 AUTO FEEDTo printer When "Auto Feed" in the menu is set as
16, 33 0 V–Signal ground.
CHASSIS GROUND
17
18 +5 VFrom printer +5V / 50mA **
19 to 30 0 V–Twisted pair return (for pin No. 1 to 11)
31 INPUT-PRIMETo printer When this signal goes to the low level,
32 FAULTFrom printer This signal goes from high to low level when
15, 34
35
36 SELECT-INTo printer In the EPSON mode, when menu item "Print
––Unused
––
level to high level.
level “0”.
tion operation end, at low level.
Indicates data cannot be received at high level.
Data can be input at low level.
valid under EPSON mode, this signal goes
to the low level and the printer generates a
line feed after receiving CR code.
–Frame ground.
printer controller is initialized. The low level
should be held for more than 0.5 ms.
paper runs out.
(Possible to indicate error and Off-Line state.)
Fixed to High (Connected to +5 V thru 3.3 KΩ)
Suppress Effective" is Yes, and the SELECTIN signal is high, the DC1/DC3 code is valid,
and invalid when the signal is low.
** When load is 50m A (more/less), volatage can drop or power can be cut off.
Description
CompatibleNibble
HostClk
?
PrtClk
PrtBusy
HostBusy
<
<
<
<
<
nDataAvail
<
<
IEEE1284
active
NOTE
Connector pin arrangement for above.
18
36
Interface specifications > 15
1
19
P
ARALLEL INTERFACE LEVELS
Low level: 0.0 V to + 0.8 V
High level: +2.4 V to +5.0 V
P
ARALLEL INTERFACE CIRCUITS
(a) Receiver
DATA BIT 1 to DATA BIT 8:
SN74LVC161284DGGR or equivalent
INPUT-PRIME, STROBE:
SN74LVC161284DGGR or equivalent
(b) Driver
ACKNOWLEDGE, PAPER END, SELECT, FAULT, BUSY
SN74LVC161284DGGR or equivalent
Signal NameR (Ω) C (pF)
R
C
0V
INPUT-PRIME471000
STROBE4747
P
ARALLEL INTERFACE TIMING CHART
DATA BIT1 to
DATA BIT8
(H)
(L)
(H)
(L)
(H)
(L)
S
UPPORT MODE
STROBE
BUSY
ACKNOWLEDGE
>Compatible
1 μs
min
DATA
1~500 μs
500 ns
max
1 μs
min
T busy
t
1t1
2~8 μs
= 1~ 4 μs
t
1
>Nibble (PnP Device ID only)
Interface specifications > 16
U
NIVERSAL SERIAL BUS
(USB)
Universal Serial Bus Specification Revision 2.0 Full Speed mode compliance.
C
ONNECTORS
Printer Side: “B” Receptacle (Upstream Input to the USB Device)
Cable Side: Series “B” Plug
C
ABLE
Length: Max. 5 m (Cable must be shielded and meet the USB Spec Rev 2.0 for normal
operation.)
The cable is not supplied with the printer.
USB
INTERFACE SIGNALS
CONTACT NUMBERSIGNAL NAME
1 Vbus
2 D3 D+
4 GND
Shell Shield
NOTE
Connector pin arrangement for above:
M
ODE AND CLASS OF DEVICE
>Full-speed driver
>Self-powered device
D
ATA SIGNALLING RATE
Full-speed function – 12 Mb/s
2
1
34
Interface specifications > 17
I
NTERFACE CIRCUIT
TxD+
Full-speed
Buffer
Rs
+ 3.3V
S
IGNAL LEVEL
Input/output level
PARAMETERSYMBOLMIN.MAX.UNITS
Input levels:
High (driven)V
High (floating)V
LowV
Output levels:
LowOL0.00.3V
High (driven)OH2.83.6V
Output signal crossover
voltage
TxD-
V
IH
IHZ
IL
CRS
Rs
2.0V
2.73.6V
0.8V
1.32.0V
Signalling levels
Bus State
Differential “1”(D+)-(D-)> 200mV and D+ > V
Differential “0”(D-)-(D+)> 200mV and D- > V
Single-ended 0 (SE0) D+ and D- < V
Data J state:
Low-speed
Full-speed
Data K state:
Low-speed
Full-speed
Idle state:
Low-speed
Full-speed
Resume stateData K state
Start-ofPacket (SOP)
End-of-Packet (EOP)
Disconnect
(at downstream port)
Connect
(at downstream port)
ResetD+ and D- < V
Differential “0”
Differential “1”
Differential “1”
Differential “0”
D- > V
D+>V
Data lines switch from Idle to K state
SE0 for ≥ 1 bit time1followed by a J
state for 1 bit time
SE0 for ≥ 2.5μs
Idle for ≥ 2msIdle for ≥ 2.5μs
RequiredAcceptable
(max)D+ and D- < VIH(min)
IL
(min) and D+ < VIL(max)
IHZ
(min) and D- < VIL(max)
IHZ
(max) for ≥ 10msD+ and D- < VIL(max) for ≥ 2.5μs
IL
Signalling Levels
(min)(D+)-(D-)> 200mV
IH
(min)(D-)-(D+)> 200mV
IH
D- > V
(min) and D+ < VIH(min)
IHZ
D+ > V
(min) and D- < VIH(min)
IHZ
SE0 for ≥ 1 bit time1followed by a J
state
NOTE
The width of EOP is defined in bit times relative to the device type receiving
the EOP. The bit time is approximate.
3 Received Data RD To printer Data to printer
4 (Note 2)Request to Send RTS From
6 (Note 3)Data Set Ready DSR To printer Indicates that data can be sent
7 Signal Ground SG — Signal ground
11 (Note 2)Supervisory
20 (Note 2)Data Terminal
5, 8 to 10,
12 to 19,
21 to 25
Data
Send Data
Ready
— — — Unused
PG — Frame ground
TD From
printer
printer
SSD From
printer
DTR From
printer
Data from printer
Signal to indicate printer cannot
receive data in printer Busy/Ready
protocol
(Printer receives data after
confirming this signal as a SPACE.)
Signal to indicate printer cannot
receive data in printer Busy/Ready
protocol
Signal to indicate printer cannot
receive data in printer Busy/Ready
protocol
NOTE
1. Connector pin arrangement for above:
13
25
1
14
(Viewed from interface cable side)
2. SSD signal output can be selected from pins 4, 11, 20 by the MENU.
3. DSR signal valid/invalid can be set by the MENU.
E
LECTRICAL CHARACTERISTICS
Signal levels
RS-232C interface signal levels are as specified below, and meet the EIA Standard RS232C:
–15 to –3 V: MARK = OFF = LOGIC “1”
+15 to +3 V: SPACE = ON = LOGIC “0”
Interface specifications > 22
Line driver
INPUT
Equivalent to HIN202
+5V
400kΩ
OUTPUT
NOTE
The above figures are the standard values for a load of 3 Kohm, 15 pF.
Line receiver
NOTE
If the power on the input side is OFF, the output of the receiver becomes high
(+2.4 V or more) at TTL level.
OUTPUT
+5V
-5V
Equivalent to HIN202
INPUTOUTPUT
5kΩ
+3V
-3V
INPUT
+10V
-10V
+30V
-30V
Interface specifications > 23
I
NTERFACE TIMING CHARTS
Receiving timing chart
DSR signal
RD
NOTE
DSR signal valid/invalid can be set by the Menu.
SSD signal timing chart
SPACE
MARK
SPACE
MARK
RD
DTR
Start bit
Stop bit
0.5 bit
More than 0 μsMore than 300 μs
Data
Stop bit
SPACE
MARK
0.5 bit Start bit
MAX 5 ms
BUSY
READY
R
ECEIVING MARGIN
Receiving margin is more than 37% at any baud rate.
D
ESCRIPTION OF COMMUNICATION PROCEDURES
The types of protocol can be selected by menu communication procedures:
READY/BUSY, X-ON/X-OFF and READY/BUSY & X-ON/X-OFF (ML5720/ML5721).
I
NTERFACE CONTROL CODE
The following function codes are used in the high-speed serial interface:
COMMAND CODE
DC1 (17)D (11)H
DC3 (19)D (13)H
NOTE
Characters to be printed according to the parity error indication code (40)H
will differ depending on the setting of the printer character set. Refer to the
printer User’s Guide.
Interface specifications > 24
Ready/Busy protocol
Block formatFree
Error indicationThe parity error indication is printed as
character 40(H).
Busy state indicationThe busy signal turns on (becomes Busy)
Timing chart
RDDATA 1DATA 2
Threshold of the
characters in
the buffer
DTR
X-ON/X-OFF protocol
Block formatFree
Error indicationThe parity error indication character is
8K
512
0
when the space in the interface buffer has
become less than 256 bytes. The busy signal
turns off (becomes Ready) after 200 ms or 1
second has passed if 256 bytes have
recovered within 200 ms or 1 second. If the
recovery time exceeds 200 ms or 1 second,
the busy signal turns off (becomes Ready)
immediately after the recovery has occurred.
ON (BUSY)
OFF (READY
200 ms or 1 second minimum
converted into code 40(H).
Timing chart
NOTE
If data is transferred when the printer is still BUSY, the printer sends a DC3
code every time it receives data.
Busy state indicationThe DC3 will be sent to the transmission si de
immediately after the space in the interface
buffer has become less than 256 bytes to
indicate that receiving is impossible. The
transmission of the DC3 stops when data
receiving has stopped. If the recovery time
for 256 bytes is within 200 ms or 1 second
after the DC3 is sent, DC1 will be sent 200
ms or 1 second after the recovery to indicate
that receiving is possible. If th e recovery
time exceeds 200 ms or 1 second, the DC1
is sent immediately after the recovery has
occurred.
256 characters or less
RD
TDPRINTING
BUSY state
ON
OFF
DATA 1
3
3-C
3
-
-CD
CD
D
200 ms or 1 second minimum
Waiting for BUSY
state to be free
DATA
1CD
Interface specifications > 25
L
OCAL TEST FUNCTION
Circuit Test mode setting
Diagnostic: Test set by menu
Test connector: Connect the test connectors as shown below to the interface connectors.
2
TD
3
RD
4
RTS
5
Equivalent to Cannon DB-25P
CTS
CD
SSD
DTR
DSR
8
11
20
6
Circuit Test mode function
After the settings outlined in Circuit Test mode setting are completed and power is turned
on, the serial interface checks the message buffer memory and interface driver and
receiver circuits, then prints all characters. To start and stop this test, press the SEL button
on the front of the printer. Details of this test are explained below.
1.Print the program revision with two numerical characters.
2.Print “LOOP TEST.”
3.Check memory for message buffer.
Print “GOOD” if memory check is OK, and print “BAD” if memory check fails.
4.Output LOW to DTR, RTS, and SSD signals. If a CTS, DSR, or CD signal is HIGH,
print “BAD”. If the CTS, DSR, and CD signals are all LOW, print “IF GOOD”.
Output HIGH to DTR, RTS, and SSD signals. If a CTS, DSR, or CD signal is LOW, print
“IF BAD.” If the CTS, DSR and CD signals are all HIGH, print “IF GOOD.”
5.Transmit characters from code 20H to 7FH by TD signals. At the same time,
characters are received from the RD signal and stored in the message buffer.
6.Print the characters that were stored in the message buffer as indicated in Step 5.
7.Repeat from Step 1.
Interface specifications > 26
O
PERATOR INTERFACE
O
PERATOR PANEL FUNCTIONS
The operator panel buttons and LEDs are located as follows:
Button functions depend on the printer state which can be any one of:
>Print Mode (for a summary of print modes and features see “Appendix B – Print