Asynchronous RS-232 DB25F 19.2 kbits/s Asynchronous/ synchronous RS-232 DB25F 125 kbits/s Asynchronous RS-232 DB25F 125 kbits/s Asynchronous RS-232 DB25F 125 kbits/s Asynchronous RS-232 DB25F 56 kbits/s Synchronous RS-422 DB25F 56 kbits/s Asynchronous RS-485 Terminal RS-530 block 2.048 Mbits/s Asynchronous RS-232 DB25F 600 kbits/s RS-422 RS-485 (2- or 4-wire) T1/E1 Terminal block 2.048 Mbits/s T1/E1 Terminal block 2.048 Mbits/s T3/E3 Coaxial 2.048 Mbits/s Asynchronous/ RS-232, synchronous RS-530, V.35 DB25F 2.048 Mbits/s *Data circuit-terminating equipment/data terminal equipment. The Model TC1540 The TC Communications Model TC1540 fiber-optic modem represents a very versatile copper connection extender. This is due to the ability of the TC1540 to be obtained with an RS-232, RS-422, RS-530, or RS-485 two- or four-wire interfaces for point-to-point communications. Figure 8.2 The TC Communica- tions Model TC1540 fiber-optic modem. POWER (Photograph courtesy D-STNC LOCLE TC COMMUNICATIONS FIRES RMTLB OPTIC of TC Communica- CONNECTIVITY SIGGEY Model TC1540 tions.) DRYMO RS485 OPTIC MODEM 10-14VDC OPTIC If focus on Figure 8.2, the applicable electrical connector is locat- will ed below you the top edge of the fiber-optic modem. That connector and be DB25 socket connector for RS-232 or RS-422 (RS-530) interfaces and four a terminals for an RS-485 interface capable of supporting two- four-wire connections. The TC1540 is powered by DC, with a 9- to 12-V-DC power input connector located below the top right edge of Figure 8.2. Thus, a wall outlet within close proximity of each TC1540 is an important consid- eration. If you turn your attention to the left portion of Figure 8.2, you LED will note a row of eight dual inline program (DIP) switches and eight local indicators. The DIP switches govern such functions as enabling a electrical loopback for diagnostic testing, defining the looping of received data to transmit data, generating a simulated 2-Hz transmit pulse signal that is transmitted via the attached fiber cable to a