840Hxl - Serial Protocol
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9
Serial Protocol
The
840Hxl
can be controlled via the serial port using the commands described in
this section.
9.1
Command Format
Commands must be in the following format:
0xEB, address, command, length of data, data 1, …data n, checksum
where the following table describes the command components.
Command
Component
Description
0xEB
Fixed command start byte
address
Device address. This is always 0x90 for the 840Hxl
command
Command to be sent (see
Section
length of data
How many bytes sent/received (from data 1 to data n)
data 1, data n
One or more command variables within the range 0x01 to 0xFA and excluding 0xEB
checksum
Optional—Checks whether the sending/receiving frame is valid.
Check sum = A C Data Data 1+…+Data n
For example, EBH, 90H, 01H, 01H, F3H, 85H
Check sum = 90H + 01H + 01H + F3H = 185H
Note
: The checksum gets the low 8 bits, for example, if the check sum = EBH, then check sum =
14H
9.2
Device Response
The device responds as follows:
0xEB, 0x90, command, 0x01, answer, check sum
where
answer
is one of the values described in the following table.
Command
Component
Description
0xF1
Either:
–the device received the wrong address and returns no response
–the device gets information about Errors and Alarms
0xF2
The data is out of range. The command is not executed
0xF3
The device is currently controlled by the buttons. The command is not executed
0xF7
The data length is incorrect. The command is not executed
0xFC
The data is out of range. The command is not executed
