Micro-Aide LDM-1 Bedienungsanleitung PDF herunterladen (Seite 39)

APPENDIX B

TXDOT APPLICATIONS

INTRODUCTION

The LDM-1 is used in a variety of applications by the Texas Department of

Transportation. It is frequently used in conjunction with the MICRO-AIDE

Local Control Unit (LCU) and PSDM and ADU modules manufactured by

Coastcom. Changeable message signs, vehicle detectors and camera pan-and-

tilt systems utilize the LDM-1 to facilitate RS-232 communications.

NETWORK CONFIGURATIONS

The LDM-1 can be used in point-to-point and multi-drop network configura-

tions. Figure 3 on page 10 and Figure 4 on page 11 illustrate the basic differ-

ences in the two types of networks. Several key points concerning each

network are described in the following sections.

OINT-TO-POINT

The point-to-point configuration is typically used when only a pair of devices

need to communicate with each other. A single LCU communicating with a

PC would be an example.

Another typical example occurs when a controller needs to communicate with

a roadside camera. In many cases the controller does not support hardware

handshaking. The LDM-1 will not transmit data until it receives an RTS and

then issues a CTS. Consequently, the RTS signal must be forced to a continu-

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Micro-Aide LDM-1 Bedienungsanleitung Seite 39