Current Loop Interface; Current Loop Transmitter; Current Loop Receiver; Isolation - CEL-MAR ADA-13021 User Manual

ADA-13021
– terminal mode,
– modem emulation mode,
– console mode,
– user mode.
However, in the case of the Current Loop converter, it will not be able to work properly in these modes, as they relate to the full RS232
interface.

2.4. CURRENT LOOP INTERFACE

2.4.1. CURRENT LOOP TRANSMITTER

The Current Loop transmitter in the ADA-13021 was made as a passive 0-20mA(TTY), having low energy short circuit protection on
TX+ and TX- lines. By the correct connection of the transmitter with power source I1, Current Loop transmitter 0-20mA can operate as
active. The transmitter diagram is shown on figure below.

2.4.2. CURRENT LOOP RECEIVER

The ADA-13021 converter has passive RX receiver having low energy short circuit protection on TX+ and TX- lines.
By the correct connection of the receiver with power source I2, Current Loop receiver 0-20mA can operate as active.
The receiver has signalization of non current flow through optocoupler. It is indicated by the red LED RX on front panel of the
converter. This LED lit when it is:
- not connect transmitter to receiver,
- wrong connection of transmitter to receiver,
- broken connection of transmitter to receiver.
The diagram is shown on figure below.
I1 +
I= 0 / 20mA
I
I1 -
I1 – Transmitter's
Current source

2.5. ISOLATION

Converter ADA-13021 has 3-way galvanic isolation on level 1kV= or 3kV=, depend on version described in section VERSIONS.

3. INSTALLATION

This chapter will show how to connect ADA-13021 to Current Loop bus, LAN/WAN network and power supply and how to use it.
In the purpose of minimization of disruptions from environment is being recommended to:
● apply multipair type shielded cables, which shield can be connected to the earthing on one end of the cable,
● arrange signal cables in the distance not shorter than 25 cm from powering cables,
● apply cable of adequate cross-section due to voltage drops for converter powering,
● use Interference suppression filters for power supply converters that are installed within a single object.
● not supply converter from power circuit device that generates large impulse interference such as transmitters, contactors,
TX+
I= 0 / 20mA
TX-
Passive Transmitter
Fig. 3. Diagram of the transmitter & receiver ADA-13021 Current Loop
3-WAY ISOLATION
ETHERNET
Fig. 4. Isolation structure
I2 +
I= 0 / 20mA
I2 -
I2 – Receiver's
Current source
Current Loop
Power Supply
10 - 30VDC
6
RX+
I
RX-
Passive Receiver