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System 2020 XT C
ONNECT
Modbus connection (option)
7 - 1
ba75970e01 10/2012
7 Modbus connection (option)
The IQ S
ENSOR
N
ET
system can be connected to a Modbus system in
the following ways:

with an MIQ/MC2 controller with the Modbus option

with an MIQ/2-MOD Modbus module
The present section only describes the connection with the MIQ/MC2-
MOD controller.
7.1 Modbus checklist
The following checklist supports you when planning, projecting and
installing a Modbus plant with the IQ S
ENSOR
N
ET
. For smooth
operation, you should be able to answer all questions with "Yes".

Is the [bus system] (bus segment) installed without branch lines?

Was the correct Modbus cable used (cord type A according to
EN 50170)?

Are the poles of the signal lines A line and B line correctly connected
at all bus connections?

Is it guaranteed that there is no short-circuit between A line, B line
and cable shielding?

Is the shielding installed free of interruptions?

Are the guidelines for shielding and grounding being observed, and
doesn't any unallowed potential equalization current flow
via the shielding?

Is the maximum cable length (per bus segment) observed for the
corresponding baud rate?

Do all devices support the required baud rate?

Are exactly two terminators switched on at the ends of the [bus
system] (bus segment)?

Are the terminators supplied with voltage so the following applies:
U
B line
- U
A line
> + 500 mV?

Do all devices have individual bus addresses?
Further instructions for the installation and operation of a
Modbus network are given on the Internet under www.mod
-
bus.org. Especially recommendable is the "Aufbaurichtlinie
PROFIBUS/FMS" (installation guideline) issued by the
PNO PROFIBUS user organization, (PNO order number
2.111) with many practical installation tips that apply to
Modbus systems as well.