Thermo Scientific 42i Instruction Manual page 240

System Description
I/O Components
Analog Current
Outputs (Optional)
Analog Voltage
Inputs (Optional)
Digital Relay
Digital Inputs
8-10 Model 42i Instruction Manual
The optional I/O Expansion board includes six isolated current outputs.
These are software configured for any one of the following ranges, while
maintaining a minimum resolution of 11 bits:
0-20 mA
●
4-20 mA
●
The user can calibrate each analog output zero and span point through
firmware. At least 5% of full-scale over and under range are also supported,
but may be overridden in the firmware, if required.
The analog outputs may be assigned to any measurement or diagnostic
channel with a user-defined range in the units of the selected parameter.
The current outputs are independent of the voltage outputs. The current
outputs are isolated from the instrument power and ground, but they share
a common return line (Isolated GND).
Eight analog voltage inputs are used to gather measurement data from
third-party devices. The user may assign a label, unit, and a conversion
table (2 to 10 points). Each point in the conversion table consists of an
analog input voltage value (0-10.5 V) and a corresponding user-defined
reading value. Only two points are necessary for linear inputs, however a
larger number of points may be used to approximate non-linear inputs. All
voltage inputs have a resolution of 12 bits over the range of 0 to 10.5 volts.
The instrument includes one power fail relay on motherboard and ten
digital output relays on the digital output board. These are reed relays rated
Outputs
for at least 500 mA @ 200VDC.
The power fail relay is Form C (both normally opened and normally closed
contacts). All other relays are Form A (normally opened contacts) and are
used to provide alarm status and mode information from the analyzer, as
well as remote control to other devices, such as for controlling valves during
calibration. The user may select what information is sent out each relay and
whether the active state is opened or closed.
Sixteen digital inputs are available which may be programmed to signal
instrument modes and special conditions including:
NO Measure Mode
●
NO
●
x
Zero Gas Mode
●
Measure Mode
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