User Guide

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MAXTXRETRY - Maximum Transmit Retries
Volatile Address = 0x52; Non-Volatile Address = 0x07
The value in the MAXTXRETRY register sets the number of transmission
retries performed if an acknowledgement is not received. If an
acknowledgement is not received after the last retry, exception EX_
NORFACK is raised. Figure 52 shows examples of the command.
The time between retries depends on the current baud rate. Figure 53
shows the time between retries based on baud rate. The elapsed transmit
and acknowledgment time is (retries+1) × (PacketTransmitTime + Timeout).
Figure 52: HumPRO
TM
Series Maximum Transmit Retries Command and Response
HumPRO
TM
Series Acknowledgement Timeout Times
Baud Rate Timeout Time
9,600 50ms
19,200 50ms
38,400 30ms
57,600 30ms
115,200 30ms
Figure 53: HumPRO
TM
Series Acknowledgement Timeout Times
HumPRO
TM
Series Maximum Transmit Retries
Read Command Read Response
Header Size Escape Address ACK Address Value
0xFF 0x02 0xFE
0x52
0x07
0x06
0x52
0x07
V
Write Command
Header Size Address Value
0xFF 0x02
0x52
0x07
V
DATATO - Transmit Wait Timeout
Volatile Address = 0x50; Non-Volatile Address = 0x05
When a byte is received from the UART, the module starts a timer that
counts down every millisecond. The timer is restarted when each byte is
received. The value for the DATATO register is the number of milliseconds
to wait before transmitting the data in the UART receive buffer. The default
setting for this register is 0x10 (~16ms delay).
If the timer reaches zero before the next byte is received from the UART,
the module begins transmitting the data in the buffer. This timeout value
should be greater than one byte time at the current UART baud rate with a
minimum of 0x02. It should not be set any value less than one byte time as
unpredictable results could occur.
If the timeout value is set to 0x00, the transmit wait timeout is deactivated.
In this case, the transceiver waits until a number of bytes equal to the
UART Byte Count Trigger (BCTRIG) have been received by the UART. All
of the bytes are sent once the trigger has been reached. Figure 50 shows
examples of the commands. Figure 51 shows the minimum timeout values
based on baud rate.
Figure 50: HumPRO
TM
Series Transmit Wait Timeout Command and Response
HumPRO
TM
Series Minimum DATATO Values
Baud Rate Minimum DATATO
9,600 3ms
19,200 2ms
38,400 2ms
57,600 2ms
115,200 2ms
Figure 51: HumPRO
TM
Series Transmit Wait Timeout Minimum Values
HumPRO
TM
Series Transmit Wait Timeout
Read Command Read Response
Header Size Escape Address ACK Address Value
0xFF 0x02 0xFE
0x50
0x05
0x06
0x50
0x05
V
Write Command
Header Size Address Value
0xFF 0x02
0x50
0x05
V