I.R.I.S. FLAME MONITORING SYSTEM P522 - Manual (Page 31)

IRIS MODEL P522 APPLICATION MANUAL
Page 31
The BASIC BURNER START CIRCUIT shown in
Figure 12 is a basic circuit requiring only two pieces
of external hardware for each burner:
1. Master Relay with at least two nor-
mally-open contacts rated for load.
2. DADE Timer, with two instant close/
timeout open contacts.
* * *
1. Bryant, Design of Fail-Safe Control
Systems, Power, January, 1976.
2. Bryant, Is Your Plant’s Control Sys-
tem Safe?, Power, August, 1979.
3 Fischer, Are PLCs Suitable for Emer-
gency Shut-Down Systems?, Presented
at 43
rd symposium for the process in-
dustries, Texas A & M University,
1988.
MODULE COMMUNICATIONS
The P522 communicates with any host computer that
has an RS-232 serial I/O port and supports ASCII
character code transmission at 4800 baud (or, in cur-
rent revisions of the processor chip, at 4800 or 9600
baud). The baud rate is displayed with the module
address in the current versions (see SETTING AD-
DRESSES, section). The data transmitted to and
from the P522 is over two twisted pairs that are dif-
ferentially driven and received according to the RS-
422 standard. The differential mode allows long wire
runs in harsh, electrical environments.
MODBUS COMMUNICATION
Modbus Communication for IRIS P522 Flame Moni-
toring System Signal Processor.
Introduction
Modbus Communication protocol allows the P522
to communicate with any process controllers or hu-
man-interface host computers that support this pro-
tocol. The P522 processor status and settings are
organized as 23 4X holding registers and five 0X
discrete registers. For more information on Modbus
protocol, please refer to Modicon’s Modbus Proto-
col Reference Guide (PI-MBUS-300 Rev E).
Communication Setting
P522 can communicate only in Modbus RTU mode,
with the following configuration:
· 9600 baud
· 8 data bits
· no parity
· 1 stop bit
The factory default of a P520/P522 station number
is 0. It is important to change the station number so
that there is no duplicate stations. To change or check
the station number:
· Press and hold Reset button for 4 seconds.
· The 4 LED digits will show the baud
rate and the station number. The 2
leftmost digits are the baud rate (96 or
48); the 2 rightmost digits are station
number from (0 to 63).
· Press up/down button to change the
station number.
· Press Store button to save station number.
Protocol Detect
P522 with firmware version 5.0 still supports the
existing IRIS protocol. After power-up, processor
will listen for both protocols. Once the protocol has
been detected, communication must remain in this
protocol until the unit is powered off.
MODBUS RTU Function Supported
Four Modbus functions are supported:
· 01 Output Coil Read
· 03 Holding Register Read
· 06 Preset Single Holding Register
· 16 Preset Multiple Holding Register