24
| Tritex
®
TTX Series DC Actuator Installation & Maintenance Instructions
Curtiss-Wright | Rev D | PN75667 | 8/1/22
Figure 26
–
4-20 mA Output Connection
4-20 mA Output Specifications:
Description
Specification
Output Current Range
3 to 21 mA
Load Range
200 to 1100 Ω (see table above)
Output Accuracy
±0.2% of span
Output resolution
12 bits
Update rate
0.5 ms
have enough voltage is to determine the voltage required for
each device in the loop at 20 mA and make sure the loop power
supply has enough voltage. If using a typical 24 V source for
the loop and having only one input device along with the Tritex
TTX output, it would be highly unusual for a loop to run out of
voltage. However, if an output of 20 mA is expected from the
Tritex TTX and the actual loop current is less, check that there
is enough loop voltage. If the 4-20 mA input circuit appears
as a resistance, the maximum resistance that may be used
depends on the loop supply voltage. It is possible to convert the
4-20 mA signal into a voltage by running it through a precision
resistor.
Loop Supply
Voltage
Maximum Impedance
@ 20 mA
Minimum Impedance
@ 20 mA
12 V
200 Ω
200 Ω
15 V
350 Ω
200 Ω
24 V
800 Ω
200 Ω
30 V
1100 Ω
200 Ω
If the Tritex TTX actuator is powered down, the isolated part
of the 4-20 mA output circuit could remain active since it is
powered separately. A watchdog feature sets the 4-20 mA
output to an off-scale low output of approximately 2 mA when
actuator main and logic power are removed.
12-30V
Loop
Supply
+
-
+
-
External
Controller
4-20 mA Input
Loop
4-20 mA +
+20 mA Output
4-20 mA -
Tritex TTX IA4
Option
V/I
Conv
D/A
Converter
Isolation
From CPU
4.16 ABSOLUTE FEEDBACK
The Tritex TTX080 comes standard with multi-turn absolute
position feedback. The system consists of a base magnetic
feedback system that is always absolute over one turn and a
low power battery-backed multi-turn counter. The counter will
track the motor’s position, as long as battery voltage is present.
Multi-turn absolute feedback allows a system to be powered
off and re-started without having to re-establish a position
reference through a Home move or manual positioning, even if
a machine is packed up and relocated.
The multi-turn absolute position feature can be disabled,
and the low battery condition ignored, if desired. The battery
can then be removed eliminating the need for any battery
maintenance. Keeping I/O power on continuously can also
maintain a position reference under most conditions and
provides some other advantages in a system.
4.17 ABSOLUTE FEEDBACK BATTERY INFORMATION
Battery Life is typically 2 years from time of product purchase.
4.17.1 Low Battery Voltage
When the battery voltage gets below 3 V, a low battery condition
will be set. This condition is typically set to generate a warning
status on the Fault Enable tab of the System Setup page. The
warning status can then be assigned to one of the outputs.
The battery voltage can be displayed on the Diagnostic page
while on-line with the actuator or read by any communications
connection. The type of battery used will only have about 1% of
charge remaining when this indication occurs.
When battery voltage gets too low to maintain the count value
the Homed Status will be off on the subsequent power up,
requiring the actuator to be re-homed. A low or dead battery
does not keep the system from running. It just means a Home
will required after a power-down.
