VIPA CP 240 RS232, Manual

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Chapter 6 CP 240 - M-Bus Manual VIPA System 200V
6-10 HB97E - CP - Rev. 11/30
The FCB bit alternates at successful communication. An unchanging FCB
summons the terminal device to send the last telegram again. The lack of
an answer from a slave is accounted after 330 bit times plus 50ms. The
master firstly assumes that an error occurred in the connection level. It
repeats the transfer of the same telegram for up to two times. If there is still
no answer from the slave, the bus receives a pause of 33 bit times.
The same procedure starts when the master receives a defective respond
from the slave.
Baud rate 33x 330x
300 110 1100
2400 13.8 137.5
9600 3.4 34.4
Bit time in ms
For the addressing of the slaves the values 1 to 250 are available. Not
configured (new) slaves have the primary address 0.
The addresses 254 and 255 are to be used as broadcast address. Using
255, the master sends information to all participants, but does not receive
an answer. Using 254, every slave answers with its address. If you are
having more than one slave this causes collisions. Therefore the address
254 should exclusively be used for test purposes.
The address 253 shows a secondary addressing. The addresses 251 and
252 are reserved for future extensions.
The CI field defines the purpose of the transmitted telegram. The data
fields are always sent with the lowest value byte first (LSB first).
Slave
→
Master
CI field Application Defined at
70h Sending of an error
state User group March ´94
71h Sending of an alarm
state User group March ´94
72h Respond with
variable data
structure EN1434-3
73h Respond with fix
data structure EN1434-3
FCB bit
A field
CI field