B&B Electronics VFG3000 - Manual - Manual (Page 49)

A DVANCED C OMMUNICATIONS W ORKING WITH M ODEMS
R EVISION 1 P AGE 33
even if you want a permanent connection, you must enter a suitable timeout so as
to allow the detection of dead links. This implies that so-called permanent
connections may still drop on occasions, but since the client will immediately
reestablish the link, this is not an issue.
• The Additional Init string is used with non-direct links, and provides a series of
AT commands to be used to initialize the modem. The initial AT prefix is not
required. Several commands may be combined by simply placing one after the
other. The exact string that will be required for your modem is dependent upon
its internal software, so if you contact Technical Support for assistance, be sure
to have exact make and model information available.
• The SMS Support property is used to enable Short Message Service messaging
when using a GSM modem. In order for SMS messaging to operate properly,
you will also have to enable the SMS Transport using the Mail icon in the
Communications window as described above.
• The Logon Username and Logon Password properties are used to define the
credentials that the remote client must provide in order to be allowed to connect
to this device. The username is not case sensitive, while the password is.
Fieldbus Gateway Manager’s PPP implementation will ask its peer to use CHAP
authentication to avoid transmitting or receiving plaintext password, but will
fallback to using PAP if the remote client does not support CHAP.
• The Local Address property is used to define the IP address to be allocated to the
local end of the connection. This will thus be the IP address of the Gateway for
this link. Please note that this must not be the same as the IP address of the
Gateway’s Ethernet port, as every physical IP interface must have a distinct IP
address. The default value will work in most situations, unless your network
design demands that you use a different setting.
• The Remote Address property is used to define the IP address to be allocated to
the remote end of the connection. It is used together with the Remote Mask
property to determine what packets will be routed to this connection. For most
applications, a mask of 255.255.255.255 will be used, thereby instructing
Fieldbus Gateway Manager to send via this interface only those packets directly
bound for the remote client. A mask of 0.0.0.0, by contrast, will allow all packets
that do not specifically match another interface to be forwarded to the remote
client, presumably for further forwarding to the intended host. Intermediate
masks may be used to control exactly which packets are sent.