Hitachi H Series Instruction Manual page 141

supplier.
(3) Use shield line to connect power supply to the module, isolating from other cables
(for I/O, etc.). (Ground the shield line on the power side.)
(4) Power supply line for external supply to the module:
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0.75 mm or more in sectional area, 1 m long max.
(5) Avoid occurring noise in the 5 V DC line by installing a noise filter in the AC/DC
line of the constant-voltage power supply for external supply.
(6) Set the output voltage of the constant-voltage power supply for external supply to
5.00 to 5.20 V at the external 5 V DC input terminal table of the optical link
module. Use the digital voltmeter for voltage measurement.
3.4 Connection and Activation
● Cable connection
Make connection of coaxial cable and optical cable among CPU links in such a manner
that a loop is constituted in the entire link system, with TxD connected to RxD of the
adjacent station
The cable length between two adjacent stations should be 500 m max. (In the case of
optical cable is 1km)
However, the entire cable length in the system (gross total of cable lengths among
stations) should not exceed 1000 m. (In the case of optical cable is 15 km)
● Method for Activation of the Link System
(1) At the occasion of activation of a link system, there are no restrictions in the order of
power ON for stations.
However, linking operation will not be commenced until the power for station No.0
(master station) is ON.
(2) At the time of activation of the link system for the first time, in order to check for
overlap of set station numbers, turn ON the power for stations other than station
No.0 and finally turn ON the power for station No.0. An error will be indicated
for the overlapped stations.
(3) When the power for station No.0 (master station) is OFF after linking operation was
commenced, master station move processing is executed, and linking operation is
restarted on termination of this move processing.
In this case, the master station moves to the station (temporary master station)
having the station number that is smallest next to 0.
Since then, the master station moves to the station (temporary master station) having
the station number that is smallest excluding the master station, each time when the
power for the master station is OFF.
However, if the power for the master station and the power for the station
(temporary master station) having the station number that is smallest
excluding the master station are OFF simultaneously during operation, the
linking operation will terminate.
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