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3-5
IMSBR08-E2
3
Using the RS-422A/485 Communication Interface (/C3 Option)
(The following figure illustrates the case when the host computer’s interface is RS-232.)
Terminator (Built-in) 120
Ω
, 1/2 W or more
#
1
Do not connect terminator to
#
1 to
#
n–1
#
2
#
n
(
#
n
≤
31)
Terminator (externally attached)
FG
SG
RD B
RD A
SD B
SD A
(SG)
(B)
(A)
(B)
(A)
FG
SG
RD B
RD A
SD B
SD A
(SG)
FG
SG
RD B
RD A
SD B
SD A
(SG)
(B)
(A)
SG
T/R(B)
T/R(A)
Host
computer
Converter
RS-232
RS-422A/485
terminal on the
Recorder
COM-K
* When our communication converter COM-K (sold separately) be used.
Note
• The method used to eliminate noise varies depending on the situation. In the connection example, the
shield of the cable is connected only to the recorder’s ground (one-sided grounding). This is effective when
there is a difference in the electric potential between the computer’s ground and the recorder’s ground. This
may be the case for long distance communications. If there is no difference in the electric potential between
the computer’s ground and the recorder’s ground, the method of connecting the shield also to the computer’s
ground may be effective (two-sided grounding). In addition, in some cases, using two-sided grounding
with a capacitor connected in series on one side is effective. Consider these possibilities to eliminate
noise.
• When using the two-wire type interface (Modbus protocol), the 485 driver must be set to high impedance
within 3.5 characters after the last data byte is sent by the host computer.
CAUTION
For converters that do not have the SG pin, they can be used without using the signal ground. For
details, see the manual that came with the converter.
On some non-recommended converters, the signal polarity may be reversed (A/B or +/- indication). In this
case, reverse the connection.
3.2 Terminal Arrangement and Signal Names and the Connection Procedure of the RS-422A/485 Communication Interface
Summary of Contents for SBR-EW100
Page 1: ...IMSBR08 E2 SBR EW100 EW180 Recorder Communication Interface User s Manual...
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