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RS232 Serial Buffer
Subject to error and alteration
Manual
RS232 Serial Buffer
Models 88102
88256
88257
88409
88410
Release 1.0
W&T
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RS232 Serial Buffer
© 12/2002 by Wiesemann & Theis GmbH
Subject to errors and changes:
Since we can make mistakes, none of our statements should be
used without checking. Please let us know of any mistakes or
misunderstandings you are aware of, so that we can recognize
and eliminate them quickly.
Perform work on and with W&T products only as described here
and only if you have read and understood the manual fully. Unauthorized use can result in hazards. We are not liable for the
consequences of unauthorized use. When in doubt, check with
us or consult you dealer!
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RS232 Serial Buffer
Subject to error and alteration
RS 232 Serial Buffer
W&T RS232 Serial Buffers are used for fast buffering of serial
data between an RS232 data transmitter and RS232 receiver.
Function
The buffer works bi-directionally at a maximum transmission
rate of 115.2kbps and allows separate configuration of the input and output port with respect to transmission speed, data
format and handshake procedure. In the direction of the receiver the entire memory capacity minus the reverse channel
capacity of 4kB is available. This memory is reserved for buffering data from the peripheral to the computer.
Configuring the buffer
Before starting up for the first time, the buffer ports must be
configured for the desired transmission parameters.
Serial parameters
On the rear side of the buffer are three DIL switch blocks, with
the center (S2) block used for configuring the input port and
the right (S3) block the output port. The assignments for these
two DIL switch blocks is identical and can be found on the part
label. The ability to configure both ports separately permits you
to work on the computer side with a significantly higher transmission speed than the peripheral allows. This can drastically
increase the efficiency of the buffer.
In addition, you can use the buffer as a converter between two
RS232 devices whose transmission parameters or handshake
procedure are not otherwise compatible.
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RS232 Serial Buffer
Modes
In standard mode (S1.8 = „off“) the RS232 Serial Buffer functions like a data buffer using a FIFO principle. The data leave
the buffer on the output in exactly the same order as they were
written to the buffer by the computer. Pressing the „copy“ key
in this mode causes the entire buffer contents to be output
again, whereas „reset“ clears the buffer contents.
In block mode (S1.8 = „on“) the computer can write as many
data blocks as desired to the buffer, which the buffer then administers as separate print/plot jobs. The buffer recognizes the
end of a data block from a pause in the transmission of at least
15 seconds. Each individual job can be output as often as desired by pressing the „copy“ key. The „next block“ key activates
output of the next stored job. After outputting one data block,
the buffer stops outputting until the „copy“ or the „next block“
key is pressed. The „reset“ function clears the buffer contents
in this mode as well.
Pin assignments and buffer connection
The input of the buffer is implemented as a 25-pin SUB-D
socket using DTE, so that as a rule the printer/plotter cable already present between the computer and buffer can be used.
The buffer output uses a 2m long serial cable with a 25-pin
SUB-D male using DCE at its end, which in most cases can be
plugged directly in to the peripheral.
In a very few cases it may be necessary to jumper pins 5 and 6
inside the 25-pin SUB-D male connector. An example for connecting the buffer to a 9- and 25-pin PC and to a plotter is
shown in the illustration below:
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RS232 Serial Buffer
Subject to error and alteration
Diagnostics
Starting up an RS232 port is often problematical, since both the
pin assignments and the transmission parameters need to be
correct in order to ensure error-free data transmission. To check
the configuration the Serial Buffer provides two functions, the
settings dump and the Power/Error LED, which can be very useful during installation.
Configuration dump
Pressing and holding down the „Reset“ key while turning on the
RS232 Serial Buffer and then releasing it causes the buffer to
send its current configuration on the output port.
The output is in HPGL format, so that the text is readable for
printers or plotters. If the handshake configuration is incorrect,
the output will be in individual characters. An extremely slow
printout is therefore an indication that the buffer output port
handshake is not being correctly handled. Outputting the configuration on the peripheral device is a simple way of testing
communication between the buffer output and the terminal device.
2
3
5
7
20
25-pin female
connector
RS232
Serial
Buffer
PC
3 (2)
2 (3)
20 (4)
7 (5)
5 (8)
6 (6)
25 (9) pin
connector
Printer
Plotter
2
3
5
6
7
20
2
3
5
7
20
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RS232 Serial Buffer
Power-/ Error-LED
The Power LED of the buffer is normally constant-on after powering up the device. If this LED starts flashing during operation,
this indicates an incorrect data format setting. The buffer indicates detected parity and frame errors by flashing the Power
LED. Characters having frame errors are suppressed by the
buffer to prevent transmission of incorrect characters which are
generated when turning on the computer due to uncontrolled
actions on the data lines. If the Power LED starts flashing immediately after powering up the computer, this does not necessarily indicate an improperly configured data format.
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RS232 Serial Buffer
Subject to error and alteration
Technical data
Capacity: 256KB, 1MB, 4MB
Baud rate: 50..115200 baud
Data format: 7,8 data bits, no, even, odd Parity
Flow control: Hardware-Handshake or
XON-/XOFF protocol
Code conversion: Single code conversion in both
directions using EPROM patch
Supply voltage: AC adapter (included)
Current draw: approx. 100mA
Buffer input: 25-pin SUB-D female
integrated in buffer housing, DTE
Buffer output: 25-pin SUB-D male
incl. 2m cable, DCE
Housing: Plastic, 124x74x21 mm
Weight: approx. 500 g incl. power supply
Included: RS232 Serial Buffer
AC adapter for office applications
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RS232 Serial Buffer
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W&T
RS232 Serial Buffer
Subject to error and alteration
RS232 Serial TC buffer
W&T RS232 billing data buffers are used for buffering call and
billing data between telephone equipment and the evaluating
PC.
Function
The TC buffers are especially adapted versions of the standard
buffer for use with telephone equipment: The buffer output
port is always disabled after power-up so that incoming data
are not lost after a buffer reset. The interface to the PC must be
explicitly enabled and disabled using control sequences.
The utility „TK32.EXE“, which is available free of charge over the
Internet, allows the data to be read using any PC. The transmission parameters on the buffer must be set for 9600 baud, 8
data bits and „no parity“. After connecting the buffer to the
computer, you can start reading by using the following command line:
tk.com[1|2] [filename]
Buffer display elements
The two integrated LEDs on the buffer have the following meaning:
The green Power LED indicates the presence of correct supply
voltage. The red LED indicates the memory status and recognizes the following states:
OFF: The memory is empty; there are no call data.
ON: There are call data. Memory utilization is below 80% of the
available memory capacity.
FLASHING: There are call data. Memory utilization is above
80% of the available memory capacity.
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RS232 Serial Buffer
Pin assignments and buffer connection
The buffer input is implemented as a 25-pin SUB-D socket with
DTE function, so that as a rule any standard serial printer cable
can be used between the TC system and the buffer. The buffer
output uses a 2m long serial cable with a 9-pin SUB-D female
using DCE at its end, which can be plugged directly in to the
COM port of a PC.
9-pin female connector
ready to plug to PC
2
3
5
7
20
25-pin female
connector
RS232 Tele-
communication
Buffer
Tele-
communi-
cation
System
2
3
6
8
5
4
Data In
Data Out
Handshake Out
Signal GND
Handshake In
Data Out
Data In
Handshake Out
Signal GND
Handshake In
Configuring the serial parameters
On the rear side of the buffer are three DIL switch blocks, with
the center (S2) block used for configuring the interface to the
TC system and the right (S3) block the output interface to the
PC. The assignments for these two DIL switch blocks is identical and can be found on the part label.
Control sequences
Data flow between buffer and PC is controlled using code sequences whose function will be explained in brief on the following pages. The values for all code sequences are given in
hexadecimal representation.
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RS232 Serial Buffer
Subject to error and alteration
Start of data transmission
The command 1Bh 02h 0Dh outputs all the incoming data. Data
flow control is handled according to the handshake procedure
set on Switches S2.1 and S3.1.
Stopping data transmission
The command 1Bh 03h 0Dh disables the output port. All incoming data are stored. After turning on the buffer or after a
reset, the interface to the PC is always disabled.
Outputting memory resources
When the output is disabled, command 1Bh 07h 0Dh can be
used to get the memory space in % of the total capacity which
is being used to store call data. The buffer replies with a 2-byte
ASCII string plus a carriage return.
Identification
In addition to the above commands, the TC Buffer model 88410
is able of providing a serial number. The buffer replies to the
command 1Bh 15h 0Dh with its serial number in the form of a
10-byte long ASCII string plus carriage return (0Dh).
Additional modem functions for Model #88410
Setting switch S1.1 to the ON position the TC Buffer Model
88410 allows the device to work in Hayes modem mode. If more
than 80% of the memory capacity is used, the buffer itself uses
AT sequences to try and establish a connection with a computer, which reads out the stored data.
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RS232 Serial Buffer
First „ATDS=0“ + CR is output. This command causes the connected modem to dial the call number contained in its speed
call location 0 (see modem manual). Now the buffer expects
the identification command within 60s. If this does not arrive,
the buffer sends a „ATHO“ + CR, and after 10 minutes have
elapsed makes another dialing attempt.
Since modems from different manufacturers can vary widely in
their configuration options as well as in how they handle the
individual control lines, only some general prerequisites for modem operation of the TC Buffer can be described here. If you
are unsure or if there are difficulties, first consult the manual
for your modem.
Settings for modem operation on the buffer
Since the TC Buffer does not support all RS232 control lines,
only the RxD, TxD and ground lines should be connected on
the modem. Handshaking should be set for Xon/Xoff.
Settings on the modem
The internal speed dial memory of the modem must contain the
call number to be dialed when there is a memory overflow
(AT&ZO=[call number]). The evaluation and handling of the
RTS and DTR control inputs and of the CTS and DSR outputs
should be turned off (AT&DO, AT&R1, AT&SO). If possible, flow
control should be configured for transparent Xon/Xoff.
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RS232 Serial Buffer
Subject to error and alteration
Technical data
Capacity: 256KB, 4MB
Baud rate: 50..115200 Baud
Data format: 7,8 data bits, no, even, odd Parity
Flow control: Hardware-Handshake or
XON-/XOFF protocol
Code conversion: Single code conversion in both
directions using EPROM patch
Supply voltage: 5V regulated
Current requirements: approx. 100 mA 5V
regulated or Pin 25 on
the telephone equipment,
AC adaptor supplied.
Buffer input: 25-pin SUB-D female
integrated in buffer housing, DTE.
Buffer output: 9-pin. SUB-D female incl.
2m cable plug-ready for PC
Housing: Plastic housing, 124x74x21 mm
Weight: approx. 500 g incl. AC adapter
Included: RS232 Billing Data Buffer
Mini Gender Changer, #11570
AC adapter for office use.
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