Teledyne GFC 7001EM operation manual Analog Output Connections, Connecting the Status Outputs

Getting Started Model GFC7001E Carbon Dioxide Analyzer

3.3.2.ANALOG OUTPUT CONNECTIONS

The GFC 7001E is equipped with several analog output channels accessible through a connector on the back panel of the instrument. The standard configuration for these outputs is mVDC. An optional current loop output is available for each.

When the instrument is in its default configuration, channels A1 and A2 output a signal that is proportional to the CO concentration of the sample gas. Either can be used for connecting the analog output signal to a chart recorder or for interfacing with a datalogger.

Output A3 is only used on the GFC 7001E/EM if the optional CO2 or O2 sensor is installed.

Channel A4 is special. It can be set by the user (see Section 7.4.6) to output any one of the parameters accessible through the <TST TST> keys of the units sample display.

To access these signals attach a strip chart recorder and/or data-logger to the appropriate analog output connections on the rear panel of the analyzer.

		ANALOG OUT
	A1	A2	A3	A4
+ -		+ -	+ -	+ -

	Figure 3-7:	Analog Output Connector
	Table 3-4: Analog Output Pin-Outs
PIN	ANALOG OUTPUT		VOLTAGE SIGNAL	CURRENT SIGNAL
1	A1		V Out	I Out +
2			Ground	I Out -
3	A2		V Out	I Out +
4			Ground	I Out -
5	A3		V Out	I Out +
	(Only used if CO2 or
6	O2 Sensor is		Ground	I Out -
	installed)
7	A4		V Out	I Out +
8			Ground	I Out -

3.3.3.CONNECTING THE STATUS OUTPUTS

The status outputs report analyzer conditions via optically isolated NPN transistors, which sink up to 50 mA of DC current. These outputs can be used interface with devices that accept logic-level digital inputs, such as Programmable Logic Controllers (PLCs). Each status bit is an open collector output that can withstand up to 40 VDC. All of the emitters of these transistors are tied together and available at D.

NOTE

Most PLC’s have internal provisions for limiting the current that the input will draw from an external

device. When connecting to a unit that does not have this feature, an external dropping resistor must be

used to limit the current through the transistor output to less than 50 mA.

At 50 mA, the transistor will drop approximately 1.2V from its collector to emitter.

Teledyne Analytical Instruments 39