I.R.I.S. FLAME MONITORING SYSTEM P522 - Manual (Page 6)

IRIS MODEL P522 APPLICATION MANUAL
Page 6
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.
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
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
+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.
W IR IN G SIDE VIEW - C O VER R EM OV ED
C O NN E CT SH IEL D
TO TER M 3
U SE S HR IN K TUB IN G
R ED
G R EE N
B LA CK
W H ITE
SH IELD
+V
G N D
SC
SIG
G N D
SIG
P 522
+24V DC
G N D
SH UT TER
D RIV E
G N D
SIGN AL
FIGURE 2 - WIRING OF VIEWING HEAD