Campbell Scientific AVW200 AVW200-series Vibrating Wire Interfaces - Page 107

I.2.1 Datalogger to MD485, I.2.2 MD485 to MD485, Appendix I.

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Appendix I. Using MD485 Multidrop Modems with AVW200 Interfaces Connects to another MD485 via the CABLE2TP Connects to the datalogger's RS-232 port or the AVW200's RS-232 port via a null modem cable Connects to earth ground via an 8 AWG wire FIGURE I-4. MD485 and its connectors. I.2.1 Datalogger to MD485 The 18663 Null Modem Cable is used to connect an MD485 with the CR800, CR850, CR1000, or CR3000 datalogger. One end of the null modem cable attaches to the RS-232 port on the MD485, and the other end attaches to the RS-232 port on the datalogger (see FIGURE I-4). I.2.2 MD485 to MD485 The connection between MD485s is made with a CABLE2TP two-twisted pair cable with shield. Insulation colors are red/back and green/white. One pair is used for the differential data ("A" connects to "A", "B" connects to "B"), and one line of the other twisted pair is used for the signal ground (third connection on the MD485 terminal block). This is shown in FIGURE I-4 and FIGURE I-5. The cable shield should be connected to a chassis or earth ground (NOT the signal ground) at one end as shown in FIGURE I-5. I-3

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Appendix I.
Using MD485 Multidrop Modems with AVW200 Interfaces
FIGURE I-4.
MD485 and its connectors.
I.2.1
Datalogger to MD485
The 18663 Null Modem Cable is used to connect an MD485 with the CR800,
CR850, CR1000, or CR3000 datalogger.
One end of the null modem cable
attaches to the RS-232 port on the MD485, and the other end attaches to the
RS-232 port on the datalogger (see FIGURE I-4).
I.2.2
MD485 to MD485
The connection between MD485s is made with a CABLE2TP two-twisted pair
cable with shield.
Insulation colors are red/back and green/white.
One pair is
used for the differential data (“A” connects to “A”, “B” connects to “B”), and
one line of the other twisted pair is used for the signal ground (third connection
on the MD485 terminal block).
This is shown in FIGURE I-4 and FIGURE
I-5.
The cable shield should be connected to a chassis or earth ground (NOT
the signal ground) at one end as shown in FIGURE I-5.
Connects to another MD485 via
the CABLE2TP
Connects to earth ground
via an 8 AWG wire
Connects to the datalogger’s
RS-232 port or the AVW200’s
RS-232 port via a null modem cable
I-3