Model IR400
36
9.4 Environmental Specifications
Temperature Range:
Operating
-40°F to +167°F (-40°C to +75°C)
(Ethylene only)
-40°F to +140°F (-40°C to +60°C)
Storage
-76°F to +185°F (-60°C to +85°C)
Humidity Range
:
5 to 99% RH non-condensing
Accuracy is not affected by humidity as long as no
condensation accumulates on the windows
9.5 Communications
9.5.1 RS-485 Interface
The Model IR400 has built-in serial communications in the form of a half duplex RS-485 digital
serial interface designed to conform to EIA-485 specifications. The format is in binary data
transferred at 9600 baud with 1 start bit, 8 data bits, 1 stop bit and no parity.
The “bus master” sends a command message to the IR400, which is comprised of 5 bytes of
data in the following format: The first byte is the address of the slave device (IR400). The
second byte is the Command Word. The third byte is the Command Data. The last two bytes
are a 16-bit checksum calculated by performing a 16-bit addition of the first three bytes of the
message and placing the result in the check sum bytes.
A “1" in the most significant bit of the Command Word (byte 2), tells the IR400 to change the
settings to those given in the Command Data (byte 3).
A ”0" in the most significant bit of the Command Word (byte 2), tells the IR400 to return to the
current settings. In this case the Command Data (byte 3) will be all “0’s”.
The IR400 then responds by sending back a 5-byte message in the following format: The first
byte is the address of the IR400. The second byte is an echo of the Command Word sent by
the “bus master”. The third byte is the data requested by the Command Word. The last two
bytes are the 16- bit check sum.
9.5.2 Modbus RTU
A programming manual is available from the General Monitors website that gives details on all
the available Modbus RTU commands.
9.5.3 HART
The IR400 HART Field Device Specification provides details on HART commands. The
specification is available from the General Monitors website.
Summary of Contents for IR400
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Page 15: ...Model IR400 11 Figure 5b IR400 Mounting Dimensions with a European Box ...
Page 20: ...Model IR400 16 Figure 7 Wiring Diagram from IR400 to Control Equipment ...
Page 41: ...Model IR400 37 9 6 Engineering Documentation ...
Page 45: ...Model IR400 HART Field Device Specification for Point IR Gas Detector ...
Page 78: ...Model IR400 Infrared Point Detector for Hydrocarbon Gas Applications Modbus programming guide ...