Chapter Three
Operation
Man_805U Rev 1.8
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connects to a remote station one at a time, transfers data, disconnects and connects to the
next station.
Up to five repeater addresses may be configured as part of the remote address. That is, up to
5 intermediate modules can act as repeaters between the master and slave modules.
The RS232 DTR signal can be configured to act as a disconnect signal. If so configured, the
DTR signal will force a hang-up (DCD reset) if the host device resets the DTR signal.
3.6.4
Fast Operation Controlled Mode
Not used.
3.6.5 CTS/RTS Flow Control
Flow control is a configurable parameter. On the RS232 port, if CTS/RTS is enabled, the
CTS signal will be active when the input data buffer is not full. Note that CTS/RTS is
disabled in the default configuration - if this feature is required, it must be enabled (refer
Configuration Chapter 4). If CTS/RTS is not enabled, then data will be lost after the input
buffer (2KB) is full.
3.6.6 Intermediate Repeaters
Where intermediate repeaters are configured, each repeater will re-transmit the message onto
the next address. When the destination address is reached, the destination module will
return an acknowledgment (ACK) with the reverse address structure as the received message.
If error-checking is selected, then the destination module will only return a ACK if the error
check is valid. If the error check is not valid, then no ACK message is returned. If the error-
checking function is not selected, then the destination module will return an ACK every time
it receives a message. Each repeater will re-transmit the ACK message until it is received by
the source module.
The source module will calculate a waiting time for the acknowledgment - this time is based
on the radio baud rate, the message length (number of bytes) and the number of repeaters. If
the source module does not receive an ACK, it will transmit the same message again. The
805U will transmit the message up to five times. If it does not receive an ACK after the 5
th
attempt, it will assume communications failure and reset its DCD status. The unsuccessful
message will not be re-transmitted and will be lost.
