Rockwell Automation T8017 Trusted Peer to Peer Communications - Manual (Page 8)

Trusted
TM
Communication Software Package T8017
Issue 10 Mar 08 PD-T8017 8
1. Peer Network
The Peer Network provides communication of safety data between up to forty Trusted TM systems per
peer network. The data can be transferred between individual systems or from one system to several
systems at the same time using multicasting.
A peer network consists of one or more Ethernet networks connecting together a set of Trusted TM
systems to enable safety data to be passed between them. A network can use up to eight physical
Ethernet networks (referred to as subnets) to provide redundant data paths via up to eight separate
physical routes.
Each Trusted TM system must be fitted with a T812x processor interface adaptor for the system to
participate in peer communication. Any T812x series adaptor may be used, but adaptors in use before
TÜV release 3.5 require an update.
A single Trusted TM system can support up to four communications interfaces using peer
communication and both Ethernet ports on the communications interface can be used for peer
communication at the same time. This provides a maximum of eight physical peer ports per controller,
each of which connects to a subnet. These can be divided between different peer networks or all
assigned to one network as required.
Communications interaction via the peer network is on a master/slave basis with a single master per
subnet. Each communications interface Ethernet port may be configured as master or slave. Each
subnet is capable of supporting forty peers.
Simplex, dual or multiple redundant networks are supported. Eight peer networks are the maximum
number that may be supported by a single Trusted
TM system. Where a redundant network is
employed, the most recent information received is used. Data integrity is checked via a CRC of the
packet data sent between systems.
Network subnets may be assigned to modules and ports as desired. Normally, subnets of the same
redundant network would use separate communication modules to achieve the highest level of
hardware fault tolerance.
The information to be transferred between Trusted TM systems is defined within the application
programs using input and output boards in the standard form. The boards configure data blocks of 16
or 128 boolean points, 16 or 128 analogue points and relevant status information. Boolean and
analogue boards are ‘complex equipment’ within the IEC1131 toolset.
Each peer data block must have a unique identity on the peer network. The output board sets up a
block of data which includes the network ID number (1 to 8), the ID number of the peer that is sending
the data (1 to 40) and an index number that uniquely defines that block of data within the sending
peer’s list of output data blocks (1 to 64). These identities are described later in this document. The
data block is sent to the destination peer, chosen with another ID number. The receiving input board is
given these identities to enable it to recognize the data.
This mechanism enables data to be passed between one output board and one input board and also
allows an output to be multicast to several input boards on different controllers using multicasting.
Multicasting is a part of TCP/IP communications. A separate IP address is chosen as a multicast
destination address. This is configured as if it were another destination peer. Each receiving peer is
configured to accept data from this multicast address, as well as its true IP address. At the receiving
end, the data is presented as if it were on a private point to point link.
Each Peer to Peer point (both Boolean and analogue) is equivalent to an external I/O point. All Peer to
Peer points and boards must therefore be included in the total number of external points and boards.
The I/O point count and boards must remain within the constraints of the IEC1131 toolset.
Note: The Trusted TM communications interface will also support external communications using
Modbus over serial and Ethernet links. Using the module to support both external Modbus
communications and peer networks may slow the performance of peer communications.