RuggedCom RuggedRouter RX1100 - Manual (Page 217)

24. Configuring Serial Protocols
Revision 1.14.3 217 RX1000/RX1100™
Initially, the remote servers will place connections to the host server. The host server in turn is
configured to accept the required number of incoming connections.
The host will sequentially poll each RTU. Each poll received by the host server is forwarded (i.e.
broadcast) to all of the remote servers. All RTUs will receive the request and the appropriate RTU will
issue a reply. The reply is returned to the host server, where it is forwarded to the host.
24.1.3. Serial Protocols Concepts And Issues
24.1.3.1. Host And Remote Roles
RuggedRouter can either initiate or accept a TCP connection for serial encapsulation. It can establish
a connection from field (“remote”) equipment to the central site (“host”) equipment, vice versa, or bi-
directionally.
Configure RuggedRouter at the host end to connect to the remote when:
• The host end uses a port redirector that must make the connection.
• The host end is only occasionally activated and will make the connection when it becomes
active.
• A host end firewall requires the connection to be made outbound.
Connect from the remote to the host if the host end accepts multiple connections from remote ends
in order to implement broadcast polling.
Connect from each side to other if both sides support this functionality.
24.1.3.2. Use Of Port Redirectors
Port redirectors are PC packages that emulate the existence of communications ports. The redirector
software creates and makes available these “virtual” COM ports, providing access to the network via
a TCP connection.
When a software package uses one of the virtual COM ports, a TCP connection is placed to a remote
IP address and TCP port that has been programmed into the redirector. Some redirectors also offer
the ability to receive connections.
24.1.3.3. Message Packetization
The server buffers received characters into packets in order to improve network efficiency and
demarcate messages.
The server uses three methods to decide when to packetize and forward the buffered characters to
the network:
• Packetize on Specific Character,
• Packetize on timeout and