Yokogawa ML2 User Manual

User’s
Manual

Model ML2
RS232C/RS485
Converter

IM 77J04L02-01E

Please read through this User’s Manual before use for correct handling.
Please keep this User’s Manual for future reference.

IM 77J04L02-01E

1st Edition Sep. 2004 (YK)

Network Solutions Business Divisiion

2-9-32, Naka-cho Musashino-shi, Tokyo 180-8750 Japan
Phone: [phone] Facsimile: [phone]

1.

CAUTIONARY NOTES FOR SAFE USE OF THE PRODUCT

This User’s Manual should be carefully read before installing and oper­ating the product. The following symbol is used on the product and in
this manual to ensure safe use.

● For RS-485, 2-wire or 4-wire can be selected by DIP switch. And
for 2-wire, On/Off of Echo back function can be selected by DIP
switch. (For 4-wire, be sure to set Echo back function at Off.)

● RS-485 line is internally equipped with 220⍀ terminating resistor.
With or without the resistor can be selected with the DIP switch.

● A corresponding communication speed can be changed to eight
stages and selected with the rotary switch.
(38400, 19200, 9600, 4800, 2400, 1200, 600, 300 bps)

This symbol is displayed on the product when it is
necessary to refer to the User’s Manual for information on

4. MOUNTING METHODS

personnel and instrument safety. This symbol is displayed
in the User’s Manual to indicate precautions for avoiding
danger to the operator, such as an electric shock.

The following symbols are used only in this manual.

NOTE

Insert/pull out the main unit vertically to the surface of a
socket. Otherwise the terminals bend and it may cause a

IMPORTANT

Indicates that operating the hardware or software in a
particular manner may cause damage or result in a system
failure.

bad contact.

4.1 Wall Mounting

Unlock the stoppers (top and bottom), and pull out the main unit from
the socket. Then fix the socket on wall with two M4 mounting screws.
Insert the main unit to the socket and fix the main unit with stoppers
(top and bottom).

NOTE

Draws attention to essential information for understanding
the operations and/or functions of the product.

2.

CHECKING PRODUCT SPECIFICATIONS AND PACKAGED ITEMS

Main unit

(1) Checking the Model and Product Specifications

Check that the model and specifications indicated on the nameplate
attached to the side face of the main unit are as ordered.

(2) Packaged Items

Check that the packing carton contains the following items:

● ML2: 1

● Spacer (used for DIN rail mounting): 1

● Tag number label: 1 sheet

● User’s Manual (this manual: IM 77J04L02-01E): 1 copy

[Mounting Dimensions]

Socket

2-⭋4.5 or 2-M4

3. GENERAL

This plug-in type RS-232C/RS-485 dual directional (half duplex) con­verter has two ports of RS-232C and RS-485. Between these two
ports, isolation, level conversion and active control of driver are per­formed. This converter is mainly used to connect RS-232C of personal
computer with the instruments equipped with RS-485.

40⫾0.2

Pitch: 56 or more

5 or more

(51)

Stopper

Mounting

screws

(85)

Unit: mm

Socket

Note:
(1) More than 5 mm interval is

required for side-by-side
close mounting.

(2) Use the supplied spacer for

DIN rail mounting to keep 5
mm interval.

Main Features and Functions

● Two modes (Auto and Manual) for Active control of RS-485 driver
can be selected with the DIP switch.

Auto: When start bit is detected on RS-232C side, the converter

makes RS-485 driver active.

Manual: Active control of RS-485 driver depends on RS (Request to

Send) of outer set instrument connected with RS-232C.

1

4.2 DIN Rail Mounting

Insert DIN rail into the upper portion of the DIN rail groove at rear of
socket of the converter and fix the converter to the DIN rail with slide­lock at the lower of the converter.

Fit into here

DIN Rail

Push
DIN Rail

VIEW A

Spacer

VIEW A

(Rear of the socket)

Slide-lock

6. EXTERNAL WIRING

WARNING

To avoid the risk of an electric shock, turn off the power
supply and use a tester or similar device to ensure that no
power is supplied to a cable to be connected, before carring
out wiring work.

Wiring should be connected to the terminals on the socket of the
product. The terminals for external connections are of M3.5 screws.
Use crimp-on terminal lugs for connections to the terminals.

● Recommended cables: A nominal cross-sectional area of 0.5 mm
or thicker (0.9 mm2 or thicker of multicore twisted pair cable with a
shield is recommended) for signal cables, and that of 1.25 mm2 or
thicker for power cables.

RS-485

Power Supply

GND

6

L+

7

N–

8

Communication

6 5 4 3

7 8 1 2

TML 2-wire Signal4-wire Signal

1

SDA (–)

2

SDB (+)

3

RDA (–)

4

RDB (+)

5

NC
NC

A (–)
B (+)

SG

2

Spacer

4.3 Using a Duct

When using a wiring duct, install the duct at least 20 mm away from the
top and bottom faces of the main unit.

5. INSTALLATION LOCATIONS

● Avoid the following environments for installation locations:
Areas with vibration, corrosive gases, dust, water, oil, solvents, di­rect sunlight, radiation, a strong electric field, and/or a strong
magnetic field

● If there is any risk of a surge being induced into the power line
and/or signal lines due to lightning or other factors, a dedicated
lightning arrester should be used as protection for both this unit
and a field-installed device.

IMPORTANT

●

The power line and input/output signal lines should be
installed away from noise-generating sources. Other
wise accuracy cannot be guaranteed.

●

The grounding resistance must be 100 Ω (JIS Class D
grounding). The length of the grounding cable should
be within 20 m. Directly connect the lead from the
ground terminal (terminal no. 6) of the product to the
ground. Do not carry out daisy-chained inter-ground
terminal wiring.

●

Use of the product ignoring the specifications may
cause overheating or damage. Before turning on the
power, ensure the following:
(a) Power supply voltage and input signal value applied

to the product should meet the required
specifications.

(b) The external wiring to the terminals and wiring to

ground are as specifications.

●

Do not operate the product in the presence of
flammable or explosive gases or vapors. To do so is
highly dangerous.

●

The product is sensitive to static electricity; exercise
care in operating it. Before you operate the product,
touch a nearby metal part to discharge static electricity.

2

IM 77J04L02-01E 1st Edition Sep.10, 2004-00