7
The bit assignment for each alarm condition is shown
below:
7 6 5 4 3 2 1 0
X
command out of range alarm
0
unassigned (always "0")
X
motor alarm (no M1 motion)
X
motor alarm (no M2 motion)
0
unassigned (always "0")
X
motor current trip alarm (M1)
X
motor current trip alarm (M2)
X
low battery voltage alarm
In the following example, $A0 (1010 0000 binary) indicates
that a "low battery voltage alarm" and a "motor current trip
alarm (M1)" have been detected.
PACS
®
Command (RS#BD):
50 00 BD
Returned Data (example):
A0
Bit 0 - "command out of range alarm"
The DHC-400 detects when the analog command
input signal exceeds its maximum value (e.g., more
than 10V for a 2-10V command signal) and bit 0 is
set to "1" accordingly; note that the actuator will
run to 100% open before the motor is shut off.
When the analog input signal polarity is connected
backwards for a 0-5V or 0-10V command signal,
bit 0 is also set to "1"; note that the actuator will
run to 0% open before the motor is shut off. For a
4-20mA, 1-5V, or 2-10V command signal,
backward polarity is detected as a Loss of
Command and sets bit 0 of the Alarm Flags
($00CA) parameter instead.
Bit 1 - UNASSIGNED (always "0")
Bit 2 - "motor alarm (no M1 motion)"
When the DHC-400 turns on its M1 output to run
the actuator and does not detect any motion after a
period of time, bit 2 will be set to "1" if the motor
current was less than 0.5A. If the motor current
was greater than 0.5A, a motor stall is detected, and
bit 2 of the Alarm Flags ($00CA) parameter is set
to "1" instead. Whether the M1 direction is toward
open or closed depends on where those positions
have been set. When the DHC-400 is operated in
the manual mode from its control panel (see Figure
2), the ▲ button turns on the M1 output.
Bit 3 - "motor alarm (no M2 motion)"
Bit 3 is set to "1" in the same manner as bit 2
except for the M2 direction. The M2 direction is
associated with the ▼ button when the DHC is
operated in the manual mode.
NOTE: When bits 2 and 3 are both set to "1", this
indicates no motion detected in both directions.
The alarms can be cleared mechanically at the
actuator, but also by powering the unit down and
back up. This allows the DHC-400 to attempt
moving the actuator. A power down sequence can
also be simulated via the bus using the PACS
®
Reset parameter (see Section III).
Bit 4 - UNASSIGNED (always "0")
Bit 5 - "motor current trip alarm (M1)"
When the DHC-400 turns on its M1 output to run
the actuator and detects a motor current that
exceeds the trip current setting, bit 5 will be set to
"1". Whether the M1 direction is toward open or
closed depends on where those positions have been
set. When the DHC-400 is operated in the manual
mode from its control panel (see Figure 2), the ▲
button turns on the M1 output.
Bit 6 - "motor current trip alarm (M2)"
When the DHC-400 turns on its M2 output to run
the actuator and detects a motor current that
exceeds the trip current setting, bit 6 will be set to
"1". Whether the M2 direction is toward open or
closed depends on where those positions have been
set. When the DHC-400 is operated in the manual
mode from its control panel (see Figure 2), the ▼
button turns on the M2 output.
NOTE: When bits 5 and 6 are both set to "1", this
indicates a current trip in both directions. The
alarms can be cleared mechanically at the actuator,
but also by powering the unit down and back up.
This allows the DHC-400 to attempt moving the
actuator. A power down sequence can also be
simulated via the bus using the PACS
®
Reset
parameter (see Section III).
Bit 7 - "low battery voltage alarm"
Bit 7 is set to "1" whenever the DHC-400 detects a
battery voltage below 10VDC. While the battery
voltage is below 10VDC, communications, as well
as motor operations, are suspended, but continue
immediately after the voltage returns above
10VDC. For this reason, bit 7 remains set for 3
seconds after the battery voltage returns above
10VDC.
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