8
RS-232 DATA SHARERS
The RS-232 Data Sharer allows multiple devices, such as mainframe
controllers, terminals, etc., to share a single RS-232 line. You can use this
device to let multiple terminals or controllers share a single modem or
multiplexor port—so you spend less money on telephone-line lease charges
and modem costs.
The RS-232 Data Sharer is available in three models:
• TL601A-R2 and TL601AE-R2 (RS-232 Data Sharer 2-Port)
• TL553A-R3 and TL553AE-R3 (RS-232 Data Sharer 4-Port)
• TL554A-R3 and TL554AE-R3 (RS-232 Data Sharer 8-Port)
Each of the RS-232 Data Sharers supports the following features:
• Transparency to data.
• Transparency to data rates up to 115.2 Kbps.
• Synchronous and asynchronous data transmission.
• Either hardware priority or round-robin priority for selection of terminal
ports. In hardware priority, requests for access to the shared line are
prioritized according to ports’ letter designations: The port represented
by the letter closest to the start of the alphabet is given access. In round-
robin priority, access to the shared line is strictly sequential: Ports receive
access in alphabetical order.
• Front-panel switches for enabling and disabling the RTS (Request to
Send) signal on each input port. With this feature, you can isolate faulty
units or perform process-of-elimination diagnostics. This is because when
the RTS signal is disabled on a port, that port can’t contend for access.
• Jumper-selectable options: RTS delay (0 or 25 ms), RXD operation (gated
or broadcast mode), hardware-prioritized vs. round-robin port selection,
RTS-timeout period (32 seconds, 10 seconds, or disabled), and RTS-
timeout signal (RXD and TXD or TXD only)
In all applications, the Sharer shares a single RS-232 line among multiple
devices. Beyond that, applications will vary depending on the function of the
device connected to the Sharer’s master port. Typical synchronous and
asynchronous applications are described on the following pages.
2. Introduction