Modem Links
Overview
The TruTrack loggers can use modem links both for general
communications with a computer and to dial a pocket pager when alarm conditions occur. A
special modem adaptor is required between the logger and the modem. The connection
required for general communication is identical to that required to dial a pocket pager.
The logger is connected to a modem with a standard Download
Cable and a DLCA Download Cable Crossover Adaptor. The modem is
connect to the telephone network. The logger can now be controlled by any computer with a
modem that is connected to the telephone network. The logger can also be configured to
send a message to a pocket pager on the telephone network if user specified alarm
conditions occur.
Type of Modem that can be used
The dataloggers communicate at 19200 baud.
Any Hayes Compatible Modem that can lock the logger to modem baud rate to 19200 can be
used with these loggers. Some modems will try to autoseek the incoming baud rate from the
logger. This type of modem cannot be used with these loggers.
Making you own DLCA Download Cable
to Modem Adapter
The Download cable has a 9 pin female D
plug so it can be connected directly to a computer. The modem will have a 9 pin female D
(this may be a 25 pin female D on older modems). An adapter can be used to convert a
download cable into a "logger to modem" cable. This adapter requires two 9 pin
male D plugs (or one 9 pin male D plug and one 25 pin male D plug for older modems). This
adapter can be used with any loggers that use the three pin download cable and with SafeT
and microToT loggers. The design of this adapter has been tested with a range of 3 pin HR
loggers, SafeT and microToT loggers. A Genius(TM) 56K Modem (GM56flexE-V) was used as the
test modem. The following connections are required within the adapter:
| 9 pin male to 9 pin
male |
| Download Cable End |
Modem End |
| 9 pin male |
9 pin male |
| Pin 2 |
Pin 3 |
| Pin 3 |
Pin 2 |
| Pin 4 |
Pin 6 |
| Pin 5 |
Pin 5 |
| 9 pin male to 25 pin
male (older modems) |
| Download Cable End |
Modem End |
| 9 pin male |
25 pin male |
| Pin 2 |
Pin 2 |
| Pin 3 |
Pin 3 |
| Pin 4 |
Pin 6 |
| Pin 5 |
Pin 7 |
It should be noted that this adapter is not
symmetric so the Download Cable End and Modem End should be marked on the adapter.
