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4 tty submodule – Siemens S5-135U/155U User Manual

Page 246

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5-106

System Manual

C79000-G8576-C199-06

5.11.4

TTY Submodule

The TTY submodule is for use with the RK 512 computer link, data
transmission with procedures 3964/3964R, data transmission with the “open
driver.”

The TTY submodule complies with DIN 66 258, Part 1.

The TTY submodule can be inserted in the following CPU:

Interface Submodule ...

For Use With ...

TTY submodule

CPU 928B
CPU 948

The TTY submodule is equipped with a transmitter and receiver for 20 mA
current loop signals. Shown in the following figure is the typical circuitry for
current loop signals.

Current Direction Arrows

Transmitter

Transmitter

+

+

+

Receiver

Receiver

+

+

+

Figure 5-20

TTY Submodule: Loop Current Direction

The loop current can be fed in both by the TTY submodule and by the
partner station. Only the side supplying the current is non-floating.

!

Caution

With longer line lengths, you should arrange your line so that the transmitter
always supplies the current.

Application

Circuitry

CPUs, Memory Cards, Memory Submodules, Interface Submodules