CL4790 Hardware Integration Guide
Version 3.0
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CONN-HIG_CL4790
Interfacing to Other RS232 Equipment
The CL4790 is a DCE (Data Communications Equipment) device. Typically, devices like PCs are considered
DTE (Data Terminal Equipment) devices while peripheral devices are classified as DCE. A DCE device can
interface to a DTE device using a straight-through serial cable. When interfacing two DCE (or two DTE)
devices together, a null modem cable (or crossover cable) is required to swap the pins and convert the signals
accordingly.
Figure 3: DTE to DCE interface (all signals with
respect to DTE)
Figure 4: DCE to DCE interface (all signals with
respect to DTE)
Note: When using a pair of CL4790s to connect a PC to a peripheral unit, if you previously used a straight-
through serial cable to connect your PC to your peripheral device, you’ll need to use a straight-
through serial cable between the PC and the CL4790 and a null modem adapter, or cross-over cable,
between the other CL4790 and the peripheral device.
