Communications Document

9Morningstar Product Connectivity Manual
only a guideline for the user. Morningstar makes no guarantee that these products will
interface properly with Morningstar units. Please do all necessary research into compat-
ibility before making a purchase.
2.2.1 Serial (DB-25) / Serial (DB-9) Adapter
There are two different types of serial connectors. One has 25 pins and the other (found on
Morningstar devices) has 9 pins. Adapters are available to convert 25 pin serial to 9 pin serial.
One may be necessary, for example, if your computer has a 25 pin serial connection and you
want to directly connect to a TriStar with a 9 pin connection. These adapters usually do not come
attached to the end of a serial cable; a cable is needed in addition to the adapter.
Figure 4. DB-25 to DB-9 Adapter
2.2.2 Straight-Through Serial Cable
Straight-through serial cables connect a DTE (data terminal equipment) device to a DCE (data
communications equipment) device by matching Tx pins, Rx pins, CTS pins, and RTS pins be-
tween devices, thus the name straight-through cable. Both ends of the cable terminate in DB-9
connectors.Thesecaneitherberegular-style(cylindrical)orribboncable(at);eitheraresuit-
able for use. When using a TriStar controller, a ribbon-stylecableisneededforpropertunder
thecoverlid;aregular-stylecablewillnott.www.blackbox.comhaslow-proleribboncablesfor
purchase.
Figure 5a. Regular-style serial cable Figure 5b. Ribbon-style serial cable