© EPRAD Incorporated
All serial commands and responses are ASCII text. For testing purposes it is easy to use a terminal
emulation software program on a PC, such as Hyperterminal, to type commands and view responses
and the unsolicited messages from the eCNA. A connection can be made to the RS-232 ports or
Ethernet port using the communication parameters described above.
For example, to make an connection to the eCNA’s Ethernet port with Hyperterminal, connect using
TCP/IP (Winsock). Enter the Host Address (eCNA’s IP Address, e.g., 192.168.1.101) and the Port
Number (13000). Under File - Properties - Settings - ASCII Setup, make sure both Send line ends
with line feeds and Echo typed characters locally are checked. Enter commands exactly as they
appear in the manual.
Important Client Application Notes
1) A CAI channel will timeout after one minute. However, the connection timeout logic allows the
connection to remain open even if the connection has timed out to allow sending unsolicited
reports. But be aware, that the eCNA will close the TCP/IP connection if it is timed out and
another client requests the resource. It may be desirable to periodically send a command to the
port in order to maintain ownership of the resource.
In the case where the eCNA communications resource is already being used (open and not timed
out) by Client A and Client B tries to connect, the eCNA accepts the connection, sends the error
response (RSP,ERR,0,998,Resource Unavailable,828<CR><LF>) to Client B and immediately
closes the connection. The connection to Client A is unaffected.
2) The third parameter in all commands is the Packet Sequence Number (PSN). The PSN is a
two-byte number (0 to 65535) that should wrap at 65535. The eCNA puts the client’s command
PSN in all responses to the client. The PSN can be used to match responses with commands. The
client may increment the PSN for each new command it transmits. Incrementing PSN is optional
and if not used just fix it at 0.
3) A checksum calculation by the client is optional. If “??” is used in the command instead of a
checksum, the command is executed. The eCNA interprets this as a ‘don’t care’ value for the
checksum. This method is not recommended because it does not insure proper message error
checking. However it may be acceptable for TCP/IP communications.
4) The Request Response parameter (Y or N) appears in a command just before the checksum. This
instructs the eCNA to either send a response or not. This is available for all commands that do
not request information from the eCNA.
The response is only an acknowledgment that the command was received and not that it was
necessarily executed. The Report Event message or Status command can be utilized to
determine execution.
5) Commands exceeding 132 characters including the terminating carriage return and line feed are
discarded by the eCNA. Commands must not contain the NULL character (0x00) anywhere in the
command line.
For RS-232 communications, it is recommended that the client use hardware (RTS-CTS)
handshaking.
6) ASCII messages can be sent ‘unsolicited’ from the eCNA based on internal and external events.
These messages may be required for the application and are configured by the client using the
CONFIGURATION command. This configuration is saved to battery-backed memory, but the
configuration flags are cleared when the firmware is updated or when the battery is replaced. So
it is a good idea to always send the configuration on initial communications.
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eCNA-10 Operation and Installation Manual Version 1.270-00
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