Flowserve DDC-100 Modbus Direct-to-Host User Manual download pdf (Page 23)

40 DDC-100 Direct-to-Host Programming Guide FCD LMAIM4019-00 FCD LMAIM4019-00 DDC-100 Direct-to-Host Programming Guide 41

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Interfacing

Hardware for the

DDC-100 Network

The Flowserve Limitorque DDC-100 Network uses the RS-485 electrical standard for the network

communications medium. Because RS-232 ports are standard on most popular Host devices, Limi-

torque offers two RS-232 to RS-485 converters. These converters contain circuits that electrically

isolate the Host, improve noise immunity, and protect it from high-level voltage surges that may be

induced into the network.

RS-485 is used for the network electrical standard because it is capable of communicating data at

high rates over relatively long distances, and may be used in redundant loop or multi-drop network

topologies.

5.1 RS-232 to RS-485 Converters

Limitorque has sourced two models of the RS-232 to RS-485 converters. The primary distinction

between these models is self or auto-steering vs. steered as detailed in this section. The models

can be distinguished by the part numbers on the case of the converter. The speciﬁcations for both

models are given in Table 5.1. The dimensions of the converter enclosures are given in Figure 5.1

and the cable to connect the converter to a 25-pin serial port is shown in Figure 5.2.

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Flowserve DDC-100 Modbus Direct-to-Host User Manual Page 23