18 | UM-PP-EN-03
3.3
RS-232 Interface
The treadmill's RS-232 interface may only be used for approved medical devices.
3.3.1
Control Lines
The control only needs TxD and RxD lines. The RS-232 control lines are bridged in such a way that
there should not be any problems in communicating with a PC running under DOS or Windows.
Galvanic separation rules out the risk of any interference in the PC from the treadmill. A crossed zero
modem cable is required (as used) to connect 2 PCs with normal standard pin configuration.
The interface is configured to the following parameters:
9600 Bd / 8 Bit / no parity / 1 Stopbit
3.3.2
Software
Interface is provided with 256 byte buffer for transmitting and receiving (take place interrupt-
controlled). Commands are not interpreted until fully present in the buffer. The interpretation
proceeds with full control of the command format (commands must be correct to be executed).
Interface responds to faults with 0Dh (multiple responses if necessary) and is not blocked by incorrect
commands; the beginning of the next correct command is also recognized. Valid commands refresh
the TIME OUT (if mode is activated). Excessive values for individual parameters are reduced to the
max. tolerable levels without producing fault messages.
The configuration of the buffer means that several commands can be transmitted to the interface in
direct succession. They can be executed in sequence at max. possible speed (normal interpretation
times are in the ms range).
PC programmer is responsible for preventing overflow of transmission/reception buffer. Ensure that
no overflows occur during successive transmission of several commands which do not wait for a
response (add telegram lengths of command/response; total must always be less than 256).
