Campbell Scientific MD9 Coax Multidrop Interface - Manual (Page 9)

MD9 Multidrop Interface
5
35 MD9s @ 0.2 db 7 db (including MD9 at PC)
5,000 ft. @ 0.6 db/ 100 ft. 30 db
Coax terminator pair 6 db
Total Signal Loss 43 db
6. Telephone to MD9 Network
It is possible to access an MD9 network via telephone when the network is
miles from the PC. See Figure 6-1.
A Campbell Scientific Model COM200 Telephone Modem is used in
conjunction with a Model PS512M 12 and 5 Volt Charging Regulator to
communicate with an MD9. The COM200 and the MD9 are both supplied with
a 9 pin SC12 cable suitable for connection to the PS512M. The PS512M
provides 5 volts for system operation and performs the function of a null
modem (the COM200 & MD9 are both "modem" devices).
The PS512M requires a 12 Volt battery for operation and contains a charging
circuit to maintain the battery voltage level. The PS512M includes an AC wall
transformer for AC operation A solar panel (
optional ) may be used if AC is
unavailable.
A PS512M with a serial number less than 1712 does not supply
12 volts to the COM200 modem. Use adapter 10704 or connect
12 volts and ground to the 12 volts and ground terminals on the
COM200.
The MD9 connected to the COM200 telephone modem must have the ID
switch set to 255 (all switches open). When creating the station file in PC208
the base telephone with phone number is entered first and the MD9 with ID is
entered second.
When configuring the network in PC208W a modem device (9600 baud) is
added to a COM port, the MD9 device attaches to the Modem, and the
datalogger to the MD9. The base phone number is entered in the MD9 window
and the “Switch Setting of Remote MD9” (ID) is entered in the datalogger
window.
In order to make measurements at the telephone to MD9 location,
a datalogger with it's own MD9 is required.
NOTE
NOTE