Varec 8315 Series manual 3.2 COM1 RS-232/RS-485 J5, 3.3 COM1 RS232/RS-485 Selection Switch SW2

Hardware TankGate Interface

2.2.3.2COM1 (RS-232/RS-485) (J5)

Note! On some versions of the TankGate, COM1 is not available

RS-232 is one of the two types of high-speed serial communications channels available to interface to Host systems using several different protocols. RS-232 will operate at distances up to 100 feet, while RS-485 allows multidrop communications at distances up to 4000 feet. RS-232 can be used for flexibility in configuring other types of communications links. Other variations of RS-232 communications interfaces include radio, modem and fiber optic interfaces.

The choice of RS-232 or RS-485 is determined by the COM RS-232/RS-485 Selection

Switch SW2

2.2.3.3COM1 RS232/RS-485 Selection Switch (SW2)

Switch SW2 determines whether RS-232 or RS485 is used. Note that the Hardware

Handshaking Switch SW1 affects the operation of COM1

Figure 2-12:Com1 SW2 Switch
	EARTH
A B	NEUTRAL
	LINE		RS232
	SURGE GND
RS232	+	VFIELD
	-
COM1
	A/TXD
RS485	B/RXD
	GND	COM1	COM1
	RTS
	CTS
	TXD
	RXD	COM 0 AUX	SW2
	GND
	+15V
	+5V	POWER	RS485
	GND
	-15V

2.2.3.4COM1 Hardware Handshaking Switch (SW1)

For RS-232, there are two different settings. One setting is used if hardware handshaking (RTS/CTS) is required. The other setting eliminates the need for hardware handshaking. Set the Hardware Handshaking Switch to the ‘A’ position to use RTS/CTS when a modem or signal converter is involved and requires RTS/CTS to operate. The RTS and CTS signals will be available on terminal block J6. If the connection is direct using RS-232, jumper RTS to CTS by setting SW1 to the ‘B’ position

Figure 2-13:Com1 SW1 Switch
	EARTH
A B	NEUTRAL
	LINE		HARDWARE HANDSHAKING
	SURGE GND
RS232	+	VFIELD
	-
COM1
	A/TXD		A	B
RS485	B/RXD
	GND	COM1
	RTS		SW1
	CTS
	TXD
	RXD	COM
		0
	GND
	+15V	AUX
	+5V	POWER
	GND
	-15V

12 Installation and Operations Manual