CEL-MAR ADA-4020A, User Manual, Page: 12 / 16

ADA-4020A converter with set up addressing is listening constantly to frame on RS485 bus via RS485/422 port. If received frame
contains byte of address equal to address of converter, then another bytes of frame are received, right up to silence on RS-485 bus
equal to 'space between frames in signs'. If the frame is received correctly, the address byte is deleted and transmitted over as typical
to the Current Loop port. In case of errors in received frame, it isn't transmitted to the Current Loop. In this case should be send the
previous frame one more.
The frame received from device connected to Current Loop port is being tested of transmission errors and in case of their missing the
converter adds address to the beginning of frame and send it to RS485/422 bus through RS485/RS422 port. Frame containing errors
isn't being transmitted to RS485/422 port. In case of transmitting of frames containing more than 950 bytes converter receive only 950
bytes and next are ignored. ADA- 4020A has equipped with separate buffers for RS485/422 and Current Loop CLO, therefore
converter can operate in full duplex mode on RS-422 and RS-485 4-wire bus.
Additionally, can be set data flow control for RS485/RS422 interface according to pt. CONFIGURATION BY THE USE OF
ADACONFIG.
On a picture below are shown the possibilities of using the addressable ADA-4020A baud rate converter.
Fig.10. Connection of no addressable devices with Current Loop interface to RS485/422 bus
7. CHANGES IN THE SOFTWARE
From CPU 2.0 and software 000.007 versions, was added:
- flow data control by the use of DE signal for RS485/RS422 interfaces. Description of using new option is in pt. CONFIGURATION BY
THE USE OF ADACONFIG,
- converter operating mode factory default is set by the use of SW1 micro-switch, see pt. OPERATING MODE
ATTENTION!!!
THE SOFTWARE IN 0.007 VERSION AND UPPER WILL NOT OPERATE WITH THE CONVERTERS WITH CPU 1.0. VERSION.
IN CASE OF UPDATE THE SOFTWARE TO 0.007 VERSION AND UPPER IN THE CONVERTERS WITH CPU 1.0. VERSION
PLEASE CONTACT TO SERVICE.
12
ADA-4020A
RS-485 bus
2 - wires or
4 - wires
Addressable
device
RS-485
RS-485 bus parameters:
- baud rate 19200 bps,
- data bits 8,
- non parity,
- stop bits 2,
ADA-4020A
Address 3
CL
Current loop
ADA-4020A
Address 4
CL
Current Loop
Current Loop CL
device
ADA-4020A
Address 2
ADA-1040
RS-232
Current Loop CL
device
Current Loop CL
device
- baud rate 1200 bps,
- data bits 8,
- parity,
- stop bit 1,