Rockwell Automation T8870 Trusted 32 Channel 120V dc Digital Output Digital Output FTA - Manual (Page 7)

Trusted
TM
120Vdc Digital Output FTA T8870
Issue 8 Feb 08 PD-T8870 7
1. Description
The Trusted TM 32 Channel 120Vdc Digital Output FTA T8870 provides termination for a maximum of
32 output field loops. The 32 channels are arranged in five groups each comprising eight identical
channels. Figure 2 below shows the configuration of two channels within a group.
Figure 2 Two Channel Schematic
Indication of the presence of the field power supply is provided by a green LED (one for each power
group). The supply is then fed to each channel within the power group.
The signal to the field device is fed directly from the output module.
The cable linking the 32 channels on the output module to the FTA is terminated at the 96-way socket
SK1. SmartSlot (Version 1) signals from the module are connected to SK1. The dc field power
supplies are connected to the FTA via a 10-way terminal block PWR TB. The output signals to the
field (32-off) are connected by 2-wire arrangements terminated on 20-off 3-way terminal blocks and
2-off 2-way.
All channels need a 330KF 0.25W resistor in parallel with the load to enable the module to distinguish
between an open circuit load and a stuck-on-fault.
V_FIELD_GRP1
V_FIELD_RTN_GRP1
F
I
E
L
D
T
E
R
M
I
N
A
L
S
V_FIELD_RTN_GRP1 ( SK1 AND 2 )
V_FIELD_GRP1
PWR
TERMINALS
CHAN _1_V_FIELD_GRP1
CHAN _1_V_FIELD_RTN_GRP1
CHAN _2_V_FIELD_GRP1
CHAN _2_V_FIELD_RTN_GRP1
CONNECTIONS TO
OUTPUT MODULE
CONNECTIONS
FROM
OUTPUT
MODULE
TO
THE
FIELD