Campbell Scientific TGA100 Trace Gas Analyzer Manual - Manual (Page 85)

of the table. They are also affected by the Invert digital output bits parameter in the Miscellaneous Valve Control
Parameter screen, which defines whether an active bit will have a high voltage or a low voltage.
Pulse Samples: The duration (number of samples at 10 Hz) of the site means switching pulse. For nonlatching valves,
enter "-" to keep the bits energized during the entire site time. This parameter applies to all of the Site I/O Bits (bits 0
through 15).
5.3 MASTER/SLAVE OPERATION
Up to five TGA100s may be linked together (one master and up to four slaves) to measure gradients or site means for
multiple gas species, with each TGA100 measuring a different species. Each slave measures concentration at 10 Hz and
sends its data to the master. The master controls the sampling system valves, calculates gradients or site means for all of
the TGA100s, and stores the results on its hard disk. The results are also sent back to the slaves for display.
5.3.1 Master/Slave Setup
Communication between systems is enabled by interconnecting the transputer cards in the TGA100 PCs. For a single
system operating alone, the first two connectors on the transputer board are not used, the middle connector is connected
to the link adapter, and the two connectors on the end farthest from the computer’s motherboard are connected together
using a loop-back cable, as shown in
. When connecting two or more systems together in a master/slave
configuration, the loop-back cables must be connected from the master to slave 1, from slave 1 to slave 2 (if used), etc.
to all of the slaves, and then back to the master, as illustrated in Fig
.
Figure 5-14
Figure 5-14. Loopback Cable Connection for Standalone Operation
ure 5-15
Figure 5-15. Loopback Cable Connections for Master/Slave Operation
Newer TGA100s use a different style transputer board with a single connector. The mating cable assembly includes the
loopback cable as a mating pair of cables with DIN connectors. These must also be interconnected in a loop from the
master, to each of the slaves, and back to the master.
85