B&B Electronics RT12-2222-ZP-12 manual Typical Application 4-20 mA to Voltage Conversion

Typical Application: 4-20 mA to Voltage Conversion

This section will describe how a typical system is converted from a 4-20mA or 0- 20mA current signal to a 1-5Vdc or 0-5Vdc voltage signal.

The RT series RTU’s do not allow for a direct 4-20mA connection. A simple 250 Ohm, 1%, ¼ Watt, resistor from the input of the respective terminal to ground will convert the current signal to a voltage signal. If a 250 Ohm resistor is not available a 249 Ohm, 1%, ¼ Watt, resistor will work.

The same example is true for a 0-20mA current signal. The only exception is the voltage will swing from 0-5Vdc. If a current source is applied to a respective input without a resistor the data will not be correct and a signal error will occur.

The example below shows analog Input 1 converted from 4-20 to 1-5Vdc. Keep in mind, if an RTU is used in Peer to Peer mode, the receiving device will output a 1- 5Vdc voltage on the respective output.

Configuration Cable Description

Serial cable used in configuration and connectivity of B&B Electronics’ RT-series controllers.

Pin#	Connection (color)	Description
DB9-Pin#2	Green	TX
DB9-Pin#3	Red	RX
DB9-Pin#5	Yellow	GND
DB9-Pin#7	Black	CTS

-Use a straight-through, common, Category 5 cable (available from B&B Electronics) for connection to the RT-series RTU’s.

Manual Documentation Number: RT-12 series-4006m 27 28 Manual Documentation Number: RT-12 series-4006m

B&B Electronics Mfg Co Inc – 707 Dayton Rd - PO Box 1040 - Ottawa IL 61350 - Ph 815-433-5100 - Fax 815-433-5104 – www.bb-elec.comB&B Electronics – Westlink Commercial Park – Oranmore, Galway, Ireland – Ph +353 91-792444 – Fax +353 91-792445 – www.bb-europe.com

B&B Electronics Mfg Co Inc – 707 Dayton Rd - PO Box 1040 - Ottawa IL 61350 - Ph 815-433-5100 - Fax 815-433-5104 – www.bb-elec.comB&B Electronics – Westlink Commercial Park – Oranmore, Galway, Ireland – Ph +353 91-792444 – Fax +353 91-792445 – www.bb-europe.com