Ditel DN109/10D, Technical Manual

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TECHNICAL MANUAL
LARGE DISPLAYS DN109/NB - DN119/NB - DN189/NB - DN129/NB
CHAPTER 24 ETHERNET COMMUNICATION 24-3
This section details how the information is structured at the protocol level in order to debug
communication problems with a MODBUS frame analyzer.
If you already have knowledge of this protocol, you can go directly to section 24.2.2 where
it is explained how the information must be encapsulated in the records according to the type of
data that you want to represent, as well as the control characters that are available.
•
Read Coils: Allows to visualize the state of the internal bits or designated
physical Coils. The structure of this function is presented below:
Request
Function code 1 Byte 01h
Start adress 2 Bytes 0001h to 0005h
Number of Coils 2 Bytes 0001h to 0005h
Answer
Function code 1 Byte 01h
Number of bytes used 1 Byte N (N = # Inputs / 8)
Coil status n Bytes n = N o N+1
Error
Error code 1 Byte 81h
Exception code 1 Byte 01 or 02 or 03 or 04
Table 60: "Read Coils" function structure.
Example:
The display only has the 2nd Coil active, to know the status of all of them you can use this function.
The following frames are sent and received:
IMPORTANT: Upon receiving the byte (02h) that indicates the status of the Coils, it should be
read as follows:
0 2
X X X 0 0 0 1 0
Coil #5 Coil #4 Coil #3 Coil #2 Coil #1
Table 61: Coils status reading.
“X” indicates that it is not used or not relevant.