Terminal Function
1 Current input
2 Transmitter supply +ve
3 Common
8 Output –ve (+ve current sink)
9 Output +ve (–ve current sink)
12 ID resistor (MTL4541Y only)
13 Supply –ve
14 Supply +ve
Hazardous area Safe area
6
5
4
3
2
1
4/20mA
MTL4541 MTL4541S
+
Vs–
Vs+
20 to 35V dc
–
4/20mA
Load
Load
+
–
–
+
Com
Tx+
Input
I
I
9
8
7
12
11
10
13
14
*
ID
6.4 Analogue Input modules
The analogue input (AI) modules support 2-wire or 3-wire 4/20mA or HART transmitters
located in a hazardous area; repeating the current in other circuits to drive safe-area
loads.
6.4.1 MTL4541/MTL4541S/MTL4541Y - Repeater Power Supply
Single channel, 4/20mA, HART® for 2- or 3-wire transmitters
The MTL4541 provides a fully-floating dc supply for energising a conventional 2- or
3-wire 4/20mA transmitter which is located in a hazardous area, and repeats the current
in another floating circuit to drive a safe-area load. For HART 2-wire transmitters, the
unit allows bi-directional communications signals superimposed on the 4/20mA loop
current. Alternatively, the MTL4541S acts as a current sink for a safe-area connection
rather than driving a current into the load. Seperately powered current sources, such as
4-wire transmitters, can be connected but will not support HART communication.
* MTL4541Y is functionally identical to the MTL4541 but has an additional ID resistor
connected to terminal 12.
Figure 6.24:
Top labels for
MTL4541 &
MTL4541S
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