Siemens S5-135U/155U appendix TTY Submodule, TTY submodule can be inserted in the following CPU

CPUs, Memory Cards, Memory Submodules, Interface Submodules

5.11.4TTY Submodule

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

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

Application The TTY submodule can be inserted in the following CPU:

Interface Submodule ...

For Use With ...

TTY submodule

CPU 928B CPU 948

Circuitry	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.

±	+
Transmitter	Receiver
+	±
+	±
±	+
±	+
Receiver	Transmitter
+	±
	Current Direction Arrows

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.

5-106	System Manual
	C79000-G8576-C199-06