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4–26 EPM 5300 SERIES ADVANCED POWER METERS – INSTRUCTION MANUAL
NETWORK OF INSTRUMENTS AND LONG DISTANCE COMMUNICATION CHAPTER 4: COMMUNICATION INSTALLATION
4.3 Network of Instruments and Long Distance Communication
The RS-485 Transceiver is required for a large network of instruments.
• In a two-wire connection, a maximum of 900 instruments can be included in the
same network (Figure 4.7)
• In a four-wire connection, a maximum of 3600 instruments can be included in the
same network (Figure 4.8).
FIGURE 4–7: 2-Wire RS-485 Communication Installation Connection with Transceiver
FIGURE 4–8: 4-Wire RS-485 Communication Installation Connection with Transceiver
Use modems (dedicated or dial-up) when the instruments are located at great distances.
However, set the modem to auto answer at the recommended value of 1200 baud rate, if
noise conditions exist. Also, flow control must be disabled.
You may want to use a Modem Manager RS485-RS232 Converter
When speaking to most RS-485 or RS-232C based devices, the remote modem must be
programmed for the communication to work. This task is often quite complicated because
modems are quirky when talking to remote devices. To make this task easier, EIG has
DEVICE
DEVICE
DEVICE
DEVICE
RS-485
TRANSCEIVER
(Acts as Repeater)
RS-485
TRANSCEIVER
(Acts as Repeater)
32
TRANSCEIVERS
32 UNITS
32 UNITS
COMPUTER
DEVICE
DEVICE
DEVICE
DEVICE
RS-485
TRANSCEIVER
(Acts as Repeater)
RS-485
TRANSCEIVER
(Acts as Repeater)
32
TRANSCEIVERS
32 UNITS
32 UNITS
COMPUTER