SST Automation GT200-PN-RS, Руководство пользователя

Страница: 15 / 53

WWW.SSTCOMM.COM 15
The Master protocol works in Change of Value output mode and is executed as follows:
1. If command N is read, execute command N. Otherwise, check whether the memory mapping data contained in
the request frame of command N is changed. If there is a change, execute the command N.
2. Wait for "command delay time", N plus 1. If N is greater than the number of command, N is 0. Execute order
N.

Quick output mode
Note: Quick output is valid only if "Output Command Polling Mode" in the subnet is "Change of Value" and only
for write commands.
When the system is initialized, if a Quick output command is found under the subnet, all commands under the
subnet will be divided into two queues. Queue 1 is a Quick output command queue, and queue 2 is an normal
command queue.
The Master protocol works in Quick output mode and is executed as follows:
1. Check the commands in the “Quick Output Command” queue one by one, and execute the command if the
data of a command changes. Until the data of all commands in the queue did not change.
2. Execute a command in the normal queue. An execution index in a normal queue plus one. If the number of
commands in a normal queue is exceeded, the index value is 0. Enter 1.
As you can see from the above execution, Quick output is preferred to write commands, which is of great benefit
to the transmission of control information as soon as possible at some low baud rates (<= 19200), but this
advantage is small for high baud rates.
3.3.1.8 Byte-swap
There are four types: no swap, double-byte swap, four-byte register swap and Four-Byte Big-endian and
Little-endian Swap.

double-byte swap
When using double-byte swap, the number of bytes exchanged must be 2 times integer.
Double-byte swap is 2 bytes for unit exchange, and the exchange mode is shown in the following table:
Before exchange After exchange
Byte index Byte value Byte index Byte value
0 0x12 0 0x34
1 0x34 1 0x12

four-byte register swap
When using four-byte register swap, the number of bytes exchanged must be 4 times integer.