105BCommunication processor
12.4 Universal serial interface (USS) communication
S7-1200 Programmable controller
System Manual, 11/2011, A5E02486680-05
579
Connecting a MicroMaster drive
This information about SIEMENS MicroMaster drives is provided as an example. For other
drives, refer to the drive's manual for setup instructions.
To make the connection to a MicroMaster Series 4 (MM4) drive, insert the ends of the RS-
485 cable into the two caged-clamp, screw-less terminals provided for USS operation.
Standard PROFIBUS cable and connectors can be used to connect the S7-1200.
CAUTION
Interconnecting equipment with different reference potentials can cause unwanted currents
to flow through the interconnecting cable
These unwanted currents can cause communications errors or damage equipment. Be sure
all equipment that you are about to connect with a communications cable either shares a
common circuit reference or is isolated to prevent unwanted current flows. The shield must
be tied to chassis ground or pin 1 on the 9-pin connector. It is recommended that you tie
wiring terminal 2--0V on the MicroMaster drive to chassis ground.
The two wires at the opposite end of
the RS-485 cable must be inserted into
the MM4 drive terminal blocks. To
make the cable connection on a MM4
drive, remove the drive cover(s) to
access the terminal blocks. See the
MM4 user manual for details about
how to remove the covers(s) of your
specific drive.
B (P)
A (N)
The terminal block connections are labeled numerically. Using a PROFIBUS connector on
the S7-1200 side, connect the A terminal of the cable to the drive terminal 15 (for an MM420)
or terminal 30 (MM440). Connect the B terminal of B (P) A (N) the cable connector to
terminal 14 (MM420) or terminal 29 (MM440).
If the S7-1200 is a terminating node in the network, or if the connection is point-to-point, it is
necessary to use terminals A1 and B1 (not A2 and B2) of the connector since they allow the
termination settings to be set (for example, with DP connector type 6ES7 972--0BA40--
0X40).
CAUTION
Make sure the drive covers are replaced properly before supplying power to the unit.