YSI Data Scout Advanced - Manual (Page 22)

Leave the Modem Used check box unchecked if using a local hard-wired site network of one or more transducers connected to a
hardware serial port (e.g., COM1). However, if the Site Network is remote (connected via some transmission medium using one or
more modems), then check this box. When checked, two additional text boxes appear (figure 3.8).
Figure 3.8
The text box labeled Tel.No./IP/DNS identifies some address by which a remote modem can be located when Data Scout Advanced
starts. The type of address entered into this box depends on the type of modem(s) used and the transmission medium on the “other
side” of the COM port used (e.g., dial-up telephone line, radio, satellite, or wired TCP/IP link via a broadband internet provider):
„ If the Port list box has selected the local COM port of an analog “dial-up” modem (V92 type) installed on the PC,
then this box must contain all the digits of the Telephone Number that must be dialed to reach the remote analog
modem at the other end of the dial-up telephone line connection. The “*” character may be added anywhere in the
number sequence to introduce a delay (e.g., “9*1*757*865*7777”). This number is dialed by Data Scout Advanced
when it starts, or whenever this Xducer Site Net configuration window’s parameters are changed. Data Scout
Advanced will hang up the dial-up connection when it exits or just before it changes the Xducer Site Net window’s
parameters.
„ If the Port list box has selected a “virtual” serial port then this box should be left blank. Such a port is created by a
Port Re-Director or Virtual Serial Port (VSP) software driver installed on the PC. Throughout the rest of the
manual, the term VSP is used to refer to any such “simulated” port, and the VSP driver software must be separately
initialized before Data Scout Advanced starts. It must also be assigned a static IP Address and TCP Port # of the
remote cell phone modem (CDMA or GSM/GPRS type). In this case the transmission medium is the PC’s
broadband internet provider. Such a connection may be via a corporate LAN if fire walls are setup to permit such
TCP/IP communication. Some network providers also use a VPN (Virtual Private Network) connection to make the
modem’s static IP address operate securely.
YSI has evaluated two different VSPs. The first was tested with the AirLink ‘Raven’ modem (both GSM and CDMA
models). Be sure to disable all the NVT (RFC-2217) features of this VSP, since the AirLink does not support them.
The second VSP, called RealPort, was tested with the Digi Connect ‘Remote Gateway’ (RG) device (both CDMA
and GSM models exist, but YSI has only tested the CDMA model). RealPort is fully integrated with this device.
Both VSPs must be setup to simulate an unused COM port on the PC which must be selected from the Port list box
on the Xducer Site Net configuration window. If that port choice is not available, then the VSP driver was not
loaded and activated before Data Scout Advanced started.
Note
„ For some other types of remote modems the IP address or DNS name equivalent may be entered into this box
directly. Data Scout Advanced does not currently support such connections (possible future feature).
For local site networks (i.e., when Modem Used check box is unchecked) Data Scout Advanced uses a nominal timeout value of 2 or 3
seconds for transmitting and receiving all serial commands and responses. When a modem is used (box checked), commands and
responses take longer due to various latency problems in the communication medium (Internet, satellite, or radio link). A cell network
might have a typical ½ second latency when commands are being sent regularly. However, after a “silent” period (typically 20-30
seconds), with no commands sent, such a modem often enters a “sleep” state which requires a longer latency period of many seconds
to awake. In this case the XTime text box (figure 3.8) is used to specify this “worst-case” extra time period, in addition to the normal
timeout period. For cell phone networks YSI suggests using at least the 8 additional seconds (for a total timeout period of 11 seconds).
YSI Incorporated Data Scout Advanced 18