Yokogawa Data Acquisition with PID Control CX2000 - Manual (Page 88)

3-8
IM 04L31A01-17E
Serial Interface Converter
Recommended converter
SYSMEX RA CO.,LTD./MODEL RC-770X, LINE EYE/SI-30FA, YOKOGAWA/ML2
CAUTION
Some converters not recommended by Yokogawa have FG and SG pins that
are not isolated. In this case, do not follow the diagram on the previous page
(do not connect anything to the FG and SG pins). Especially in the case of long
distance communications, the potential difference that appears may damage the
CX or cause communication errors. 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.
For a two-wire system, the host computer must control the transmission driver of the converter
in order to prevent collisions of transmit and received data. When using the recommended
converter, the driver is controlled using the RS (RTS) signal on the RS-232.
When Instruments That Support Only the RS-422 Interface Exist in the System
When using the four-wire system, up to 32 CXs can be connected to a single host
computer. However, this may not be true if instruments that support only the RS-422
interface exist in the system.
When YOKOGAWA’s Recorders That Support Only the RS-422 Interface Exist in
the System
The maximum number of connection is 16. Some of YOKOGAWA’s conventional
recorders (HR2400 and mR, for example) only support the RS-422 driver. In this
case, only up to 16 units can be connected.
Note
In the RS-422 standard, 10 is the maximum number of connections that are allowed on one port
(for a four-wire system).
Terminator
When using a multidrop connection (including a point-to-point connection), connect a
terminator only to the CX on the end of the chain. Do not connect terminators to CXs
in the middle of the chain. In addition, turn the terminator on the host computer ON
(see the computer’s manual). If a converter is being used, turn ON its terminator.
The recommended converters require an external terminator to be attached.
However, some converters have built-in terminators.
3.3 Terminal Arrangement and Signal Names and the Connection Procedure of the RS-422/485 Interface