System Description
I/O Components
Thermo Fisher Scientific
Model 48
i
Instruction Manual
8-9
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 the motherboard and ten
digital output relays on the digital output board. These are reed relays rated
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 from 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:
●
Zero Gas Mode
●
Span Gas Mode
●
Set Background
●
Calibrate to low range span concentration
●
Calibrate to high range span concentration
●
Analog outputs to zero
●
Analog outputs to full-scale
●
External Alarms
The actual use of these inputs will vary based on analyzer configuration.
The digital inputs are TTL level compatible and are pulled up within the
analyzer. The active state can be user defined in firmware.
Analog Voltage
Inputs (Optional)
Digital Relay
Outputs
Digital Inputs
