Honeywell HA71, Technical Manual

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HA71 Digital Gas Controller
Revision 3 (04/08)
HA71 Technical Manual 2-5
Analog should be selected when the channel’s input comes from a
transmitter or monitoring device with a calibrated output such as
4-20mA. Analog with Local Cal is available when the HA71 will be
the point of calibration for the analog input. Sensor Direct is identical
to Analog with Local Cal and both activate the HA71’s Cal Mode
features (see
Section 2.2.14 ). Problems may arise if calibrations are
performed in two places upon the same signal so Cal Mode menus are
only visible when Sensor Direct or Analog with Local Cal is selected.
These selections should only be used when the input originates from
a non-calibrated signal source such as the Catalytic Bead Sensor
Input option described in section 3.1.3. This application requires the
HA71 to be used as the calibration point since the sensors have no
zero or span controls.
12-Bit Analog Inputs may be
direct from Sensor Input options
or Voltage/Current Input options
The Modbus Master RS-485
port supports eight integer types,
resolutions and formats.
Figure 2-5. Data From? Menu
2.2.5 MIN/MAX Raw Counts Menu
The Min Raw and Max Raw counts entries included in the Input Data
From: menu define the range of input counts that provide Measurement
Range read out values described in
Section 2.2.10 . This menu entry
is determined by the A/D converter resolution of the channel’s input.
For example, if the input is a 10 bit Modbus
® device with zero at 200
counts and 100% at 1000 counts, then this menu’s MIN should be set
at 200 and MAX at 1000. If communicating with the HA71’s optional
12 bit Analog Input PCB the MIN should be 800 and the MAX 4000.
If the input device’s resolution is unknown, the live counts variable
on the bottom of the screen displays actual raw A/D counts currently
being read by this channel. This reading may be used to test the input
device for what A/D counts are provided for zero and 100% if these
values are unknown. Forcing the input device to
read zero should provide the A/D counts value
needed to make this channel’s display also
read zero. Likewise, forcing the input device to
read 100% should provide the A/D counts value
needed to make the HA71 channel’s display also
read 100%.
If Modbus
® 32 BIT is selected, a Byte Order
entry appears at the bottom of the menu. This
determines WORD and BYTE alignment of data at
the remote Modbus
®
transmitter when sending it’s
4 byte IEEE Floating Point values. With the pointer
on this entry, the EDIT key toggles between the
4 possible modes. Min / Max Raw values are not
used in this mode.
Note
Each Data From: item has a matching default MIN/MAX counts
value of 20% to 100% with ± 5% over/underrange applied. If the
default value is incorrect for the input device it should be edited.