Prevac MG15 - MG15 Communication Protocols; Communication Introduction and Standards; Serial Communication Cable Selection

MULTI GAUGE CONTROLLER COMMUNICATION
6 COMMUNICATION
6.1 INTRODUCTION
This chapter is intended for users who want to use Modbus RTU, Modbus TCP (Ethernet) or ProiNet
communication links. These are communication protocols used to control the functioning of the
MG15 .
The following chapter includes general information about standards, wiring and electrical connec-
tions. It presents the connectors and wiring for serial links RS232, RS485 (Modbus RTU protocols),
Ethernet (Modbus TCP) and optionally ProiNet (Modbus RTU).
In addition, it includes advances issues, such as access to full resolution of loating point data and
user interface permissions.
6.1.1 CABLE SELECTION
This section includes general information about types of cables that should be used in the serial
communication system.
It is recommended that the digital communication network cable have the following electrical pa-
rameters:
• Rated DC resistance should be max. 100Ω/km. Generally 0.14mm

(24AWG) cables or thicker.
• Rated impedance 100Ω at 100kHz.
• With differential communication screened twisted pair should be used.
• Mutual capacitance of a pair should be max. 60pF/m (capacitance between two conductors
in a pair).
• Stray capacitance max. 120pF/m (capacitance between one conductor and all other con-
nected with ground).
Of course, selection of a cable entails compromise between costs and quality of the cable (damping
or quality of screening). For applications in an environment with high likelihood of occurrence high
levels of electrical interference it is recommended to use a cable with copper screen and ground it.
For long-distance communication use a cable with low damping.
User manual rev. 03 Page 81