6
COUNTIS ECi - Ref.: 538 470 A
RS485 MEDIA
In a standard conguration, one RS485 connection enables 32 UL* to be connected to a PC or PLC over
1200 metres using the JBUS/MODBUS® protocol.
* 1 UL = 1 Countis ECi.
Recommendations:
An LIYCY type shielded twisted pair must be used.
In a disturbed environment, we recommend using a shielded twisted pair with general LIYCY-CY shielding.
If the distance is greater than 1200 m and/or there are more than 32 COUNTIS, it is necessary to con-
nect a repeater (1 channel) or a spark arrester (2 channels) to enable the connection of additional
COUNTIS. (with communication interface over more than 1200 m)
For more information on the connection procedure, refer to the technical bulletin available on the web
site: www.socomec.com
Important:
It is essential to connect a resistance of 120 Ohms to the 2 ends of the connection; this
can be found in the product packaging. Other solutions are available (modem, bre optic, etc.); please
ask for details.
JBUS/MODBUS PROTOCOL
The JBUS/MODBUS protocol operates on a master/slave structure:
• Reading (Function 3),
• Writing (Function 6 or 16), broadcast option at address 0.
The communication method is RTU (Remote Terminal Unit) with hexadecimal characters comprising a
minimum of 8 bits.
JBUS/MODBUS TABLE
File Ref: 538471
Can be downloaded from the web site: www.socomec.fr
JBUS/MODBUS COMMUNICATION
R=120Ω
R=120Ω
R=120Ω
R=120Ω R=120Ω R=120Ω
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