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ADA-1021
● Dimensions (W x D x H) 53mm x 62mm x 90mm.
2.2. DESCRIPTION
Many devices such as PLCs, transducers, sensors, cash registers and electronic scales are equipped with as standard RS232
communication port. Standard of RS232 has restrictions on the length of the cable (the distance at which the transmission is working
properly is 15m). The solution to this problem is to use for data transmission Current Loop interface. Current Loop Interface allows to
connect with each other devices at up to several kilometres.
ADA-1021 converter is a device used to convert RS232 to Current Loop standard without interfering with data format. The converter
does not require the power to his operation from the RS232 port, supports asynchronous RS232 data transmission at up to 38.4 kbps
by two pairs of twisted-pair. ADA-1021 is equipped with a female DB-9F connector for RS232 interface connection and screw terminal
blocks for twisted-pair connections of Current Loop and power supply. DB-9 connector is made as DCE which allows to connect the
converter to the PC via the RS232 extension cable (a typical cable modem connection) without crossing Tx with Rx and RTS with
CTS. For its operation uses the signals from the RX, TX and mass SG, entered by DB-9F connector to the converter. RTS signal is
looped with CTS inside the converter and DTR with DSR and DCD. Others signals are not connected. If it is not needed looping the
above signals, can be unsolder the RTS or DTR in the plug DB-9M (pins: RTS-7, DTR-4). To Current Loop line constructed on the
ADA-1021 can be connected two converters operating in full duplex or half duplex point-to-point.
This converter has internal, low energy surge protection (600W overvoltage diodes) for each Current Loop lines however it is
recommended to use the external lightning arresters (typical protection of telephone line) for the lightning protection of lines.
Current Loop Interface
2.3. CURRENT LOOP TRANSMITTER
The Current Loop transmitter in the ADA-1021 was made as a passive 0-20mA, 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. CURRENT LOOP RECEIVER
The ADA-1021 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.
RS-232 interface
DB-9F connector
(RS-232)
ADA-1021
RS-232 to CURRENT LOOP
CONVERTER
RX
TX
PWR
CL
(CURRENT LOOP)
10 – 30
VDC
53mm
Power supply
10-24-30 VDC
Fig. 1. View
4
62mm
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