YSI 6000UPG - Manual (Page 135)

9-7
SDI12
This command activates SDI-12 mode. This is the only mode that the 6000 UPG will respond to any
SDI-12 command. To exit to command line, hit any key from the terminal connected to the
RS-232 port. The 6000
UPG
provides a confirmation before exiting. If there is no response within 5
seconds, the 6000 UPG will return to SDI-12 mode.
9.4 RS-232 INTERFACE
The RS-232 interface is provided through the standard DB25 female connector. The 6000 UPG
supports XON/XOFF handshaking. The XON/XOFF handshake uses the standard ^S character
(ASCII 19) for XOFF and ^Q character (ASCII 17) for XON. To prevent permanent XOFF that
could keep the 6000
UPG awake indefinitely and triple the power consumption, a 1 minute timer is
used to timeout the XOFF. If an XOFF is received for at least 1 minute without XON, the timer
will activate and clear all pending data from the transmitter queue and reset the queue.
9.5 FILE TRANSFER PROTOCOLS
In all three modes of operation, the 6000 UPG can log data to its internal non-volatile memory (Flash
disk). As many as 130000 basic sensor readings can be saved in the Flash disk at a time. To
retrieve this large amount of data, two file transfer protocols are provided: ASCII and Kermit.
ASCII protocol transfers all calculated readings (basic and derived sensors) in plain ASCII. A pair
of [CR][LF], in that order, is sent at the end of each line. No error detection is employed. The
transfer is initiated from the 6000
UPG command line. The 6000 UPG then waits for any character
from the host before it begins the transfer. If no signal is detected within a preset amount of time, it
will proceed with the transfer.
Kermit FTP breaks data into several small packets. Each packet requires a positive
acknowledgment before the next packet can be sent. A CRC check is performed on each packet
and request for resend is issued if an error is detected. For the limited memory space available, the
6000
UPG
only implements basic Kermit FTP. It does not support batch file transfer, data
compression, or most extended Kermit specifications. It does, however, support extended packet
lengths for increased upload efficiency. For more information on Kermit, refer to a book by Frank
da Cruz entitled, Kermit A File Transfer Protocol, Digital Press, Massachusetts, 1987. Or write to:
Kermit Distribution
Columbia University Center for Computing Activities
612 West 115th Street
New York, NY 10025
USA