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Instrument I/O Interface
The J605 I/O port is a DB-25F connector on the back of the instrument that provides numerous
specialized functions for specific industrial applications and for factory use. System integration
utilizing the 4-20mA output feature is the most common use of the I/O port.
4-20mA Output
The 4-20 mA output can be used to indicate the H
2
S reading level on a proportional scale from
4-20 milliamps for connection to certain industrial systems, such as SCADA. A 4 mA current
level always corresponds to an H
2
S reading of 3 ppb
or less, while a 20 mA current level always
corresponds to an H
2
S reading of 10 ppm or higher.
Current levels between 4 and 20 mA
correspond to H
2
S readings between 3 ppb and 10 ppm on a proportional scale, as determined by
this equation:
2
[(current in mA - 4) x 10]
H S Concentration Detected (ppm) =
16
When the J605 is powered off, either manually or automatically, the output current will drop to
3.5mA to indicate this condition. However, if the J605 is operating with the internal battery
disconnected and loses AC power, the J605’s 4-20mA circuit will continue to output the last
current value as long as power to the external current loop is maintained.
The relationship between the H
2
S concentration detected and the current level present can be
represented graphically as follows:
NOTE: This is NOT a printer connection.
It is a specialized interface. Connecting any non-AZI authorized
device to this connector may damage both the device and the J605
and may void the warranty on the J605.
