025-9567E 99
PROGRAMMING ENCODER FROM SERIAL PORT
OVERVIEW
The Model 25 may be programmed with either a generic terminal emulation program (such
as HyperTerminal™ or ProComm™) or with the M25 Configuration Utility provided by
Zetron. This section covers connecting a PC to the serial port of a Model 25 in order to
program it. It will also cover using the PC to save copies of the unit programming to a disk
file and restoring the unit with that file. PCs may also be used to log the operation of a Model
25 and to control the encoder remotely.
CONNECTING TO THE SERIAL PORT
The computer port on the Model 25 encoder is compatible with RS-232C signals and uses an
asynchronous ASCII serial communications protocol. The DE9 computer port connector
socket contains four active RS-232C compatible signals; TX DATA, RX DATA, CTS (clear-
to-send), and RMT-CTL (remote-control). Other passive signals in the computer port
connector are DTR (data-terminal-ready), and RTS (request-to-send). Of course SIGNAL-
GROUND
is also included in the connector.
The TX DATA and RX DATA are the serial transmit and receive signals. The data signals
communicate in full duplex and use eight bits per ASCII character with one stop bit and no
parity bits. The most significant bit of the eight-bit character is always zero. The baud rate
(bit rate) of the serial data may be one of three programmable rates. One second or more of a
“space” or “break” level on the RX DATA pin will cause the encoder to reset.
The CTS input signal may be used to halt the serial transmission from the “TX DATA” signal
if the signal indicates not-clear-to-send. The CTS signal is most often used by serial printers
as the busy signal. The use and “busy” polarity of this signal are programmable parameters.
The RMT-CTL (remote-control) input signal is used to enable or disable the instant call
panels and indicate the mode of operation to the encoder. Since remote control devices and
the instant call panel loop share the serial port, a signal must be provided to indicate the
desired mode of operation; either remote control mode or instant call mode. With a “space”
level on the
RMT-CTL signal, the encoder is in the remote control mode and the Instant call
panels are disabled. With a “mark” level on the RMT-CTL signal, the encoder is in the instant
call mode. When in instant call mode the level at the
RX DATA signal must be a continuous
“mark” otherwise the instant call panels may produce erroneous calls. If the level of the
RMT-CTL signal is changed while the encoder is powered, then the encoder will need to be
reset either by sending two seconds of “space” over the
RX DATA signal or by pressing the
encoder RESET key. The programmable parameters for the computer port only take effect
when the encoder is in the remote control mode.
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