Data Communication and Host Modes
meantime) until it receives an acknowledgement with this sequence number. If an acknowledgement is not received within the time‐out period (specified in S7), the data will be retransmitted. This will continue until an acknowledgement is received or the modem is reset. Likewise any UDP packets received by the PinPoint‐E are expected to have this simple header. The PinPoint‐E will issue an acknowledgement for any valid packets which are received.
To configure the PinPoint‐E for a normal UDP session, you need to set the Startup Mode Default to 73 (ATMD73). If you are using two modems, configure the Destination IP and Port in each to point to each other. Serial data will then be sent reliably between the two.
Caution: Although it adds reliability, the simple implementation of the
Reliable UDP mode in the does not check for duplicate packets.
UDP Multicast Mode
UDP Multicast mode results in any data received from the host serial port being sent to all the clients in the address list. The remote port number is taken from S53. To avoid flooding the network, the packets are sent to each client with a 20ms pause in between. The receipt of UDP packets works as in normal UDP mode (i.e. bound by the value S53 and/or AIP). Since it may take a while to transmit the data to all hosts (especially if all 20 Modbus entries are used and name resolutions are required), new data received from the host port is buffered until current transmissions to all hosts are finished.
Enter the list of target IPs in the address list (ADDR LIST). The index numbers in the list arenʹt used. Configure for a normal UDP session. Set the Startup Mode Default to 83 (ATMD83). Configure the Destination port to match the device port of the remote modems.
TCP and TCP Pad
When the PinPoint‐E is in a TCP session, all characters received on the serial port are assembled into TCP packets and sent to the modeʹs remote IP address/port, and any packets received from the remote end of the TCP connection are disas‐ sembled and dumped onto the serial line.
A TCP connection is established by one of the following methods:
•Using the Dial TCP (DT) AT command. For example, ATDT192.168.3.23/3456.
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