GE EPM 5350, EPM 5200, EPM 5300 Network of Instruments and Long Distance Communication

NETWORK OF INSTRUMENTS AND LONG DISTANCE COMMUNICATION CHAPTER 4: COMMUNICATION INSTALLATION

4.3Network 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).

DEVICE	32 UNITS	DEVICE	RS-485
			TRANSCEIVER
			(Acts as Repeater)
			32	COMPUTER
			TRANSCEIVERS
DEVICE	32 UNITS	DEVICE	RS-485
			TRANSCEIVER
			(Acts as Repeater)

FIGURE 4–7: 2-Wire RS-485 Communication Installation Connection with Transceiver

			RS-485
DEVICE	32 UNITS	DEVICE	TRANSCEIVER
			(Acts as Repeater)
			32	COMPUTER
			TRANSCEIVERS
			RS-485
DEVICE	32 UNITS	DEVICE	TRANSCEIVER
			(Acts as Repeater)

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

4–26 EPM 5300 SERIES ADVANCED POWER METERS – INSTRUCTION MANUAL