4
4
C
C
H
H
A
A
N
N
N
N
E
E
L
L
A
A
N
N
A
A
L
L
O
O
G
G
U
U
E
E
T
T
R
R
A
A
N
N
S
S
M
M
I
I
T
T
T
T
E
E
R
R
2
2
7
7
O
O
F
F
3
3
0
0
1
1
2
2
0
0
-
-
1
1
8
8
8
8
-
-
1
1
2
2
T
T
Y
Y
P
P
E
E
S
S
I
I
L
L
B
B
U
U
S
S
-
-
T
T
X
X
4
4
A
A
(
(
G
G
)
)
U
U
S
S
E
E
R
R
'
'
S
S
M
M
A
A
N
N
U
U
A
A
L
L
I
I
s
s
s
s
u
u
e
e
:
:
0
0
5
5
The analogue input terminals are separated from all other terminals by more than 50mm.
The individual analogue input channels are separated from each other by more than 6mm.
This certification allows the four channel analogue transmitter to be located wholly within
the hazardous area and the connection of intrinsically safe circuits to its various ports. The
analogue inputs can be driven from a single or four different intrinsically safe sources
because of the segregation between the four analogue input channels. For the same
reason the power supply port can be driven from the same source as the analogue inputs
or from an entirely different intrinsically safe source without the need for an assessment of
voltage or current addition.
As always, careful attention should be paid to the segregation of wiring in this configuration
as incorrectly segregated wiring could negate the segregation and safety of the transmitter.
9 SILBUS-TX4AG VARIANT
The SILBUS-TX4AG variant of the SILBUS-TX4A is exactly the same as the SILBUS-TX4A
except it has been rescaled to
only
accept a 0.44-2.2V analogue signal generated by a
TROLEX TX9042 current type analogue input card. The SILBUS-TX4AG can only transmit
the 0.44-2.2V voltage signal and can not transmit current type analogue inputs.
The SILBUS-TX4AG variant is only used in conjunction with a TX9042 current type
analogue input card as shown in the figure below.
1
2
1
4
1
5
1
6
1
7
1
8
1
9
2
0
2
1
2
2
2
3
2
4
2
5
2
6
2
7
SIG
C
O
M
+VE
-VE
CH 1
CH 2
CH 3
CH 4
H
I
L
O
I to V
H
I
L
O
I to V
H
I
L
O
I to V
H
I
L
O
I to V
4 CHANNEL ANALOGUE
TRANSMITTER TYPE SILBUS-TX4AG
-VS1
+VS1
0 to 20mA
4 to 20mA
SIGNAL
O
R
+VS1
-VS1
SIGNAL
COMMON
SILBUS NETWORK
TROLEX TX 9042
V
+
H
I
V
-
L
O
C
U
R
R
E
N
T
I
N
P
U
T
C
A
R
D
2 x 220R 5%
Figure 3 SILBUS-TX4AG connected to a TX9042
The application of using the 110
Ω ±5% sampling resistor within the TX9042 current input
card to convert the 4-20mA signal into a 0.44-2.2V for retransmission via the SILBUS-
TX4AG introduces a 5% error into the signal. For this reason the SILBUS-TX4AG should
only be used as a maintenance replacement for the discontinued ATX4AG. The SILBUS-
TX4AG should not be used for new designs. The SILBUS-TX4AG does not have set point
trip alarms.
