wtw TresCon UNO A111, Operating Manual

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Appendix TresCon UNO
8 - 10 ba43134e08 05/2017
RS485 Master bus protocol
String in transmission buffer
(max. 61 chars./block)
Enter length
Calculate and enter CRC
Initialize input buffer
Send message
Start timeout B
Wait for characters to be
received
Yes
No
Repeat-Counter = 1
Repeat-Counter
+1
Repeat-Counter > 3
IF (timeout)
IF (timeout)
Load length byte into buffer
Load address byte
Start timeout A
Wait for characters to be
received
length > 0
Start timeout A
Wait for characters to be
received
IF (timeout)
Load byte into buffer
Length = length - 1
1/2 timeout B
Wait
Yes
Response invalid
Error status:
No response
Yes
Yes
CRC
CRC correct?
Address
--
Slave address
Continuation bit set?
Response is valid
Error status = Bit 5
Slave address off
END
For write commands, the
response is an empty string.
The error status within the
Slave address is valid!
No
No
Yes
Yes
No
No
No
Timeout times:
– A = 3 byte transmis-
sion times (approx. 3.1
ms with 9600 bauds)
– B= approx. 1s