22
| Tritex
®
TTX Series DC Actuator Installation & Maintenance Instructions
Curtiss-Wright | Rev D | PN75667 | 8/1/22
Because Modbus RTU at speeds supported on Tritex TTX
cannot be considered a high-performance link, data throughput
and latency issues will generally limit the capabilities of Modbus
RTU as a multi-drop network. Due to biasing resistors at each
node and data throughput limitations, the maximum number
of devices on a network should not exceed 8. A multi-drop
network can be very useful for reporting status and changing
parameters dynamically for different “recipes”, or for providing a
single access point for Expert software connection.
Figure 23
–
Connecting multiple Tritex TTX actuators to a
Modbus master Host
In addition to the CBL-T2USB485-M8-xxx described above,
the CBL-TTIOC-SMI-xxx cable assembly available in various
lengths may be used to wire from the Tritex TTX080 connector
to terminal blocks or screw terminal connectors. This cable is
more suitable for permanent connection from one or more Tritex
TTX actuators to other devices.
Cables supplied by Curtiss-Wright have the differential signal
wires 485+ and 485-, the 0V reference for these signals 485
Com, and a shield. The 485 Com wire may not be needed but
is recommended to reduce the effect of transients on signal
quality. The 485+ and 485- signals should be a twisted pair,
especially for long runs. Total RS485 cable length may be up
to 100 m. Network topology is not important and termination
resistors are generally not required.
4.13 IA4 OPTION BOARD CONNECTIONS
T
he IA4 4-20 mA I/O option board replaces the standard I/O
board and provides one 4-20 mA isolated analog input and one
4-20 mA isolated analog output. These channels replace the
standard Analog I/O input and output channels. The IA4 option
board provides four isolated digital inputs and three isolated
digital outputs, which is a reduction from the eight inputs and
four outputs available on the standard I/O board. Due to space
limitations, Ethernet based communications are not supported
with the IA4 option, so it is not possible to combine 4-20 mA I/O
channels with Ethernet based advanced communications.
Function
8 mm Pin
Number
Wire color for
TTCOM
J5 Terminal #
485+
1
Brown
5
485-
3
Blue
6
485 COM
4
Black
7
Shield
2
Drain
8
When using the Expert software for set-up and diagnostics
an RS485 converter will be required to interface between one
of the PC communications ports and the RS485. This can
be either a USB to 485 converters, such as the Exlar CBL-
T2USB485-M8-xxx or any other standard 485 converter. See
Accessories section.
Figure 22
–
Internal RS 485 Circuit
Modbus RTU is a multi-drop network, so multiple devices, some
of which might not be Tritex TTX actuators, may be connected
to a single Modbus master. Devices on any single network
need to have unique Modbus Device ID’s before connecting
them to the network. A recommended approach to avoiding
multi-drop address collisions is that in normal operation no units
have Modbus Device address 1 and any spares or additions
at default address 1 so that a new or replacement unit can
be added and then the address changed to the operational
address. Since multiple masters are not supported, it may
be more convenient to configure units using Expert software
before final installation.
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