Convertor RS232/485 - ISO485

    Converter is avail to converse the most common interface RS232 which can be used to short distance to interface RS485.This interface RS485 is advantageous because of its noise immunity and can be apply to much longer distance (from hundreds to thousands meters) by high data transmission rate(to tens Mbit/sec).
    Converter is enclosed in DIN rail mounting box with combi - screw terminals suitable for industrial usage. Power supply 24 V. As to eliminate the difference of voltage level of these interfaces r this version with galvanic separated power supply is convenient. RS232 side is supplied from external power supply and RS485 side is supplied from built-in galvanic separated DC/DC voltage changer.

 

TECHNICAL PARAMETERS

Supply voltage

24 V DC (9 - 28 V)

Supply current max. 35 mA by 24 V DC
Input and output signals according to standards RS232 and RS485.
Minimum loading impedance for RS485 100 ohms (in both sides of the line)
Jumpers inside the box can set direction of transmission control a) AUTO setting automatically change the direction according to signal TxD, enable to connect this transmitter to systems that do not have possibility to control the direction of transmission by the signal RTS
b) RTS setting control by the signal RTS, possible to set an active level of signal RTS which can then control direction of transmission
Guaranteed speed of transmission 115 kBd
Dimensions 85(height) x 72(depth) x 22,5(width) mm
Industrial case protection IP40, terminals IP20
Working temperature range 0C to +70C
Storage temperature range -20C to +70C
Converters are resistant to reversing polarity of power supply.

Built-in pulse-overvoltage protection in RS485 side.

Direction of transmission control

Direction control Connect JP1 Mode Log. level RTS Direction of transmission
According RTS 1 - 2 1 "0" RS485 -> RS232
"1" RS232 -> RS485
According RTS 2 - 4 2 "0" RS232 -> RS485
"1" RS485 -> RS232
AUTO 2 - 3


Setting switches on PCB under the front panel:

rs1.gif (5689 bytes)

Possibility to set time delay between transmitting and receiving in AUTO mode according the table:

Setting SW1
1  2  3  4

Convenient for speed
(approx)
0  0  0  1 115 kBd
0  0  1  0 57, 6-38, 4 kBd
0  1  0  0 19 200 Bd
0  1  1  1 9 600 Bd
1  0  0  0 4 800 Bd
1  1  1  1 2 400 Bd

rs2.gif (2951 bytes)

Recommended connection for Converter ISO485


Direction of transmission AUTO switching mode
Converter connection for automatic switching of transmission -connected with DTE(PC) device by connector Cannon25 or 9

 

rs3.jpg (12022 bytes)

rs4.gif (8856 bytes)


    Notes for connection:
    2 x GND terminals are inner connected (common ground of power supply and RS232 at DTE(PC) side.
    Terminal resistors Rt value the same as line impedance (e.g.120 Ohms) are necessary for long distances (alternatively for high transmission speed)      and for reliable transfer - unreflecting line termination. These resistors are placed only to the ends of line.

    Automatic switching direction of transmission mode enable to connect the converter to systems that do not control direction by RTS signal.
    Set the automatic switching mode by connecting 2 and 3 on jumper Jp1. DIP switch sets delay of inner timer depending on transmission speed. This delay should be in practice equal to time needed for transfer one byte by given transmission speed. For example by transmission speed 19200 Bd the length of byte is 0,4ms and SW1 would be set 0100. Log. 0 on line TxD triggers inner timer and simultaneously the excitation circuit for line RS485 is switched to transmission. The excitation of line RS485 is active after last transferred byte for the time that is maximum equal the setting delay. It is necessary to guarantee no transmission from the others devices on line Rs485. Therefore it is not appropriate to set too long delay that would worsen throughput of the line RS485.
   

Direction of transmission switching by RTS signal


Converter connection for switching of transmission by RTS signal -connected with DTF(PC) device by connector Cannon25 or 9

rs5.gif (7903 bytes)

rs6.gif (7818 bytes)


        In this mode the direction of transmission is controlled by RTS signal and is activate by connecting 1-2 or 2-4 on jumper Jp1. DIP switch SW1 is able to be in any position. Direction of transmission is controlled by software that have to provide appropriate setting of RTS signal. Before sending the message it is necessary to switch the line to transmission mode and after it immediately to receiving mode. So the line can be released for the others devices. If it is possible then RTS direction control is much more advantageous. The converter is transmitting only for certain time when the message is delivered. You do not have to set transfer speed on SW1 as well.
    Power supply is not allowed to be in any connection with RS232 line so as the advantage of galvanic separation RS232 and RS485 effects. The power supply is inner connected with RS232 side by GND terminal. One GND terminal is for RS232 interface and secon d for power supply. RS485 interface is supplied by built-in galvanic isolated DC/DC converter. Power supply should have a wide range of voltage 8-30V since using switching regulator.

Converter has built-in protective circuits in Rs485 side.So it can stand pulse overvoltage that possibly occur. If there is a larger amount of converters on the same line and highest transmission speed is used then it is better to use some of them without protective circuits (to lower capacitance on the RS485 line - please consult by us). For using on long lines influenced by atmosphere electricity it is necessary to add another protection outside of the converter (fast lightning arrester etc.).

Signaling LED
TxD,RxD - switch on if log. 0 on RS232 and RS485
Dir - switch on if it is transmitting (activating RS485)
On - power supply