Sensoray 618 - Manual (Page 12)

Sensoray Model 618/619 Smart A/D 10 Programming
hardware and software, are available through the
GetFaultFlags function.
For details on this function, refer to the documentation
supplied on the distribution diskette.
5.2.3 GetFWVersion
Returns the Smart A/D firmware version number, times
100. The version number is printed on the EPROM
device that is plugged into the Smart A/D board.
5.2.4 SetHiSpeedMode
Decreases the channel slot time (Section 8.1) to enable
higher throughput.
Assuming the board is operating in the default 60Hz
rejection mode, all channel slot times are reduced from
22 milliseconds (default) to 9 milliseconds, and the board
is said to be operating in the “high-speed mode.”
Decreasing the slot time causes measurement accuracy to
be reduced by approximately 75 percent and may cause
increased measurement noise. Also, line frequency
rejection is no longer possible as the digitization period is
shorter than one line cycle.
A board reset will restore slot times to their default
values. This is the only way to resume the default update
rate after invoking the SetHiSpeedMode function.
When the high-speed mode is active, any attempt to
invoke this command again will be ignored.
5.2.5 SetReject50Hz
Increases the digitizer’s integration period from 16.7
milliseconds (default) to 20.0 milliseconds, enabling the
Smart A/D to better reject 50Hz differential noise.
This function should be used in systems targeted for
50Hz power environments.
A board reset will restore the board to the default 60Hz
rejection mode. This is the only way to return to the
60Hz rejection mode after invoking the SetReject50Hz
function.
When the 50Hz rejection mode is active, any attempt to
invoke this command again will be ignored.
5.3 Channel Configuration Functions
5.3.1 SetSensorType
Declares the type of sensor connected to a channel. By
declaring the sensor type, you are implicitly selecting the
excitation mode, measurement gain setting and
linearization curve.
Upon successful execution of this function, the onboard
microcomputer will perform all subsequent scans of the
specified channel as appropriate for the declared sensor
type.
This function has several side-effects that should be
noted:
• Sensor data is not available immediately after declaring
a channel’s sensor type. After executing this function,
sensor data is reset to zero. The maximum elapsed
time that must pass before new sensor data becomes
available is equal to ten (model 618) or nineteen
(model 619) channel slot times. Details of channel slot
timing can be found in Section 8.1.
• The channel filter constant (Section 5.3.2) is reset to
zero, effectively disabling the software filter function.
• Limit alarms are disabled and limit values are
indeterminate, as the new sensor type may have a new
type of engineering units.
Typically, the client will call this function once for each
sensor channel. Each execution of this function declares
the sensor type for a single channel, therefore eight
(model 618) or sixteen (model 619) invocations must
occur to declare all channel sensor types.
Each sensor type supported by the Smart A/D board is
assigned a unique value, called the Sensor Definition
Code. This value, along with the target sensor channel
number, is passed to the Smart A/D board as a function
argument.
Upon reset of the Smart A/D board, all channel sensor
types default to the ±5-volt input range, with 500µV
resolution, and all sensor data values are reset to zero.
Arguments: void
Returns: VersionTimes100
Arguments: void
Returns: void
Arguments: void
Returns: void
Arguments: ChannelNumber
SensorDefinitionCode
Returns: void