IRIS manual Wiring Of Viewing Head, Term Description, IRIS MODEL P522 APPLICATION MANUAL

IRIS MODEL P522 APPLICATION MANUAL

one cycle regardless of the new set points, allowing channel changes “on the fly,” so to speak. If the new flame OFF set point is equal to or greater than the current signal count, then the flame relay will de-energize on the subsequent cycle.

The pair of terminals designated RMT METER (to the left of the CHAN SEL terminals) is for the remote meter connection. This output is a current-driven sig- nal that ranges from 0 to 20 mA for remote meters, and can be switched to a range of 4 to 20 mA for DCS (distributed control system) applications (refer to sec- tion 4-20mA REMOTE OUTPUT). Connect the terminal marked “positive” to the positive meter ter- minal. This current signal can be used with a volt meter by feeding the signal to a resistor connected to the ground. The voltage developed across the resis- tor will follow Ohm’s law V = IR.

be used to communicate with the P522, and the con- nections are made to the terminals marked +TX, - TX, +RX and -RX. The transmitting, twisted pair goes to the TX terminals, and the receiving, twisted pair goes to the RX terminals.

Note: the terms “transmit” and “receive” used here with respect to the P522 will be reversed with re- spect to the RS-232 connection on the host computer. Refer to later sections in this manual for a detailed description of the software and how it is to be used with the P522.

WIRING OF VIEWING HEAD

Wiring of the viewing head is made to the terminals on the lower right side of the P522. These terminals are described as follows:

TERM DESCRIPTION

For example: a 3-volt meter can be used with a resistor of 3/.02 = 150 ohms, which will result in a full-scale reading of 3 volts for a 20mA output.

The four terminals called +TX, -TX, +RX, and -RX (to the left of RMT METER terminals) are used for the serial communication link. The serial commu- nication is achieved by using ASCII character code transmission at 4800 or 9600 baud through the RS- 232 com ports on the host computer. The P522 uses RS-422 data transmission which is over two, twisted pairs that are differentially transmitted and received, allowing long wire runs to be used through noisy environments. An RS-232 to RS-422 converter must

+V	24 VDC power to viewing head
GND	Power Ground
SC	Self-check/shutter drive signal to
	viewing head
SIG	Flame signal from viewing head

SIG GND Signal ground

Figure 2 shows a four-conductor cable to the view- ing head. Note that the flame signal wire going to terminal SIG is shielded, and the shield is terminated at both ends of the cable SIG GND.

			P 52 2
		R ED	+24V DC
W IRING SIDE VIEW - CO VER REM OVED		+V
		G R EE N	G N D
		G N D
		B LA CK	SH UT TER
		SC	D RIV E
		SIG	G N D
		G N D
	W H ITE
CO NNECT SHIELD	SH IELD	SIG	SIGN AL
TO TERM 3	FIGURE 2 - WIRING OF VIEWING HEAD
USE SHRINK TUBING

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