7
COUNTIS E13/E14
- Ref.: 542 101 A
COUNTIS E13/E14 MODBUS
6. MODBUS communication
6.1. General Information
MODBUS
®
communication is performed via a RS485 serial port (2- or 3-wire) which enables products to be used
from a PC or an API.
On a standard configuration, a RS485 port can be used to connect 32 products to a PC or a PLC across 1200
meters.
R=120Ω
R=120Ω
R=120Ω
R=120Ω
R=120Ω
R=120Ω
R=120Ω
R=120Ω
R=120Ω
R=120Ω
R=120Ω
R=120Ω
MODBUS wiring
Wiring with repeater
≈ 1200 m or 32 UL
≈ 1200 m or 32 UL
≈ 1200 m or 32 UL
Repeater
0 -> NC
0 -> NC
6.2. Recommendations
It is necessary to use a shielded twisted pair (LIYCY type). In an environment where there is interference or large
network (in terms of length) we recommend the use of a shielded twisted pair (type LIYCY-CY).
A repeater should be used to connect additional products if the distance of 1200 m and/or maximum number of 32
products is exceeded.
A 120-ohm resistor must be fixed at both ends of the link.
6.3. Communication structure
The product communicates via a MODBUS
®
protocol, which involves a dialogue using a master-slave structure. The
mode of communication is the RTU (Remote Terminal Unit) mode using hexadecimal characters of at least 8 bits.
MODBUS
®
frame structure (master -> slave exchange):
Slave address
Function code
Address
Number of words to read
CRC 16
1 byte
1 byte
2 bytes
2 bytes
2 bytes
6.4. Communication table
The communication tables and associated explanations are
available on the
COUNTIS E13/E14
documentation page online at
the following address:
www.socomec.com/en/countis-e1x
