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©
2019 Radiocrafts AS
MBUS User Manual (ver 2.01)
MBUS USER MANUAL
messages the Master can be configured to check replies from the Slave and respond differently from the Mailbox
or standard message depending on the Slave packet Access Number.
If two level Auto-message handler is used (MAILBOX.TLAM=1) an additional byte is added to the auto-message
flag register and gives:
7 6 5 4 3 2 1 0 7
6
5
4
3 2 1 0
7
6
5
4
3
2
1
0
SSSSSSSS
E
D
FCB
R
MB
ANV
SMV
MBV
R
MB2
Where in addition:
ANV
Access Number Valid
The ANV (Access Number Valid) flag is defined to tell if the
Access Number should be checked by the Master before reply.
(Strictly, the master transmission is not a “reply”, as the Master
is the primary station in unbalanced communication. But we use
the term “reply” because the Slave defines the timing by its
reception window). For the first Message in the Frequent Access
Cycle (FAC) the ANV flag is not set, as the first reply is in
response to the first initiating access (e.g. SND-NR) from the
Slave.
SMV
Standard Message Valid
The SMV and MBV flags store information about the
last sent message by the Master, if it was from a
Mailbox or if it was a Standard message, and type of
standard message. Normally these flags shall not be
altered by the user. If MBV was not set it means that a
Standard Message was sent. SMV=1 means the
message sent was a response to RSP-UD and msb of
0x38 in SSSSSSSS will be cleared. SMV=0 means the
message sent was a response to RSP-UD or ACK and
msb of 0x07 in SSSSSSSS will be cleared.
MBV
Mailbox Valid
See SMV description.
R
Reserved for future use
MB2
Mailbox level 2 (0000-1111)
Only the lsb nibble (MB2) should normally be altered by the
‘A’-command. ANV, SMV and MBV are used internally
by the module to keep track of the message sequence. These flags should be read and ‘or-ed’ when writing a new
MB2 setting.
The fla
gs are read by using the ‘O’-command (letter “O”, or lowercase ‘o’). If two level Auto-message handler is
used (MAILBOX.TLAM=1), the 3 byte flag register is returned, and an additional byte containing the last Access
Number.
The flags are set by using the
‘A’-command.
7.3 Mailboxes
With default settings mailbox messages will only be sent in reply to certain incoming message types. However, the
module can also be configured (the MBSM parameter) to use the mailbox for any incoming message. The
MAILBOX configuration parameter is used to set auto-clearing of flags for standard messages and the mailbox.
There are up to 15 mailboxes that can be used to store “pre-cooked” messages. Each mailbox is 64 bytes, except
mailbox number 15 which is 128 bytes. Mailboxes can be combined to support messages up to 255 bytes (less the
