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5.5 Physical Support
The QuickRead supports the RS232 serial communication driver.
The protocol driver needs the RX (data reception) and TX (data transmission) signals.
The protocol does not foresee the use of any control signal.
The max. number of connectable QuickRead devices is four.
5.6 Serial Communication Parameters
1.
Data Bit
7 or 8
2.
Parity even / odd / none
3.
Stop Bit
1
4.
Baud Rate 1200 / 2400 / 4800 / 9600 baud
5.7 Control on the Number of Received Characters
When the QuickRead receives the first character of the string, a timeout of 250 mS is triggered.
If the reception of this package is not completed within this lapse of time:
A condition of reception timeout error is stored.
The already received characters are considered as scrap.
Therefore, the timeout implemented on QuickRead allows to correctly reinitialise the reception
queue, even when the host transmission and the QuickRead reception are not synchronised.
In case of "retry" (if the QuickRead does not answer), the host has to guarantee a temporal
window without any transmission (duration higher than 250 mS).
5.8 Control on the Received Package
One of the following conditions implies the invalidation of the received package:
Parity error and /or framing in one of the received characters.
Number of received characters higher than 8.
5.9 Timeout for Broadcast Commands
The host has to guarantee an interval of at least 500 mS after the broadcast command is
transmitted without any new transmission.
5.10 Implemented Services
The request of a service is implemented through one of the following strings:
STRING
01
02
...
99
SHORT DESCRIPTION
Selection of QuickRead with Identifier #1 and Measure
Request
Selection of QuickRead with Identifier #2 and Measure
Request
Selection of QuickRead with Identifier #99 and Measure
Request
Figure 1 : Selection Strings
...
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