Appendix
8-20
L
_^ONMObk
Controller address (AD1, AD2)
One or more bus devices (slaves) can be selected by means of the controller address which is 2
bytes (AD1, AD2) long. The LECOM-A/B protocol supports the broadcast telegrams, i.e. a telegram
is sent to a group or all other bus devices. For this, controller addresses are reserved (see
BROADCAST, page 8-24). Controller addresses have the following structure:
AD1
AD2
The abbreviations have the following meanings:
AD1
ASCII ten-digit of the slave address (0
¼
9; 30
¼
39
hex
)
AD2
ASCII one-digit of the slave address (0
¼
9; 30
¼
39
hex
)
Block-check character (BCC)
The block-check character (BCC) is used to store the transmitted data and is generated according
to DIN 66219 (chapter 3).
Because of the program, the block-check character is generated by a XOR link from the following
digits of the SEND telegram:
•
it starts with the character directly after the STX control character
•
it ends directly after the ETX control character
–
BCC can accept the value 00
¼
FF
hex
.
EOT
AD1
AD2
STX
C1
C2
V1
...
Vn
ETX
BCC
<——————— BCC ———————>
or with the expanded addressing:
STX
”!”
CH1
CH2
...
SC2
ETX
BCC
<—————————— BCC —————————>
Telegram response
The Lenze controller must return an acknowledgement to the host. The only exception is the
broadcast telegram. This telegram does not require an acknowledgement.
The Lenze controller sends two types of acknowledgements:
•
Positive acknowledgement (ACK = 06
hex
), if:
–
no faults occur during the block storage (longitudinal and lateral parity)
–
a valid command (variable address) has been recognized
–
the variable value is within the permissible range
–
the variable value could have been changed
•
negative acknowledgement (NAK = 15
hex
), if:
–
one of the above listed conditions cannot be met.
•
No acknowledgement, if:
–
a broadcast telegram is send
–
the controller address is not correct
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