Connecting A Programming Device (Pg To Ungrounded Nodes Of An Mpi Subnet - Siemens S7-400 Installation Manual

8.7.5 Connecting a Programming Device (PG) to Ungrounded Nodes
of an MPI Subnet
Connecting a Programming Device to Ungrounded Nodes
If you configure the nodes of an MPI subnet or an M7-400 as ungrounded devices
(see Chapter 4), you should only connect an ungrounded programming device to
the MPI subnet or M7-400 device.
Connecting a Grounded Programming Device to the MPI
You want to operate the nodes as ungrounded devices (see Chapter 4). However,
the MPI at the programming device is grounded. To be able to operate the nodes
without grounding, you must connect an RS 485 repeater between the nodes and
programming device. The ungrounded nodes must be connected to bus segment 2
if the programming device is connected to bus segment 1 (terminals A1 B1) or the
programming device/OP interface (see Reference Manual, Chapter 10).
Figure 8-20 shows the RS 485 repeater as an interface between a grounded and
an ungrounded node of an MPI subnet.
Figure 8-20
S7-400 and M7-400 Programmable Controllers Hardware and Installation
A5E00069481-04
M7-400
Bus Segment 2
Grounded signals
Ungrounded Operation of the M7-400 Network
Assembling the M7-400
Bus Segment 1
Grounded signals
Programming
device
8-43