JUMO 701061, Interface Description

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2 Protocol description
10
2.3 Device address
The device address of the slave can be set between 0 and 254. Device
address 0 is reserved.
Two forms of data exchange can be distinguished:
Query Data request/instruction by the master to a slave via the corresponding
device address.
The slave which has been addressed will respond.
Broadcast Instruction by the master to all slaves, via the device address 0. The
connected slaves do not respond. A specific setpoint can, for example,
be transmitted to all slaves. In such a case, the correct acceptance of
the values by the slaves should be checked by a subsequent readout of
the setpoint.
A data request with device address 0 is not meaningful.
2.4 Timing of the communication
The start and end of a data block are marked by transmission pauses.
The maximum permitted interval between two consecutive characters is
three times the transmission time of a single character.
The character transmission time (the time taken to transmit one
character) depends on the baud rate and the data format that is used
(stop bits and parity bit).
For a data format with 8 data bits, no parity bit and one stop bit, this is:
character transmission time [msec] = 1000 * 9 bits/(baud rate)
For the other data formats it is:
character transmission time [msec]
= 1000 * (8 bits+parity bit+stop bit(s)) bits/(baud rate)
Sequence
H
A maximum of 31 slaves can be addressed via the RS485
interface.
Data request from master
transmission time = n characters * 1000 * x bits/(baud rate)
Marker for end of data request
3 characters * 1000 * x bits/(baud rate)
Processing of the data request by the slave (max. 250msec)
Response of slave
transmission time = n characters * 1000 * x bits/(baud rate)