PDP-5000EX
143
5678
56
7
8
C
D
F
A
B
E
9.1.2 COMMAND PROTOCOL
Command format
Communication protocol : Asynchronous serial communication by RS-232C
Start bit length : 1 bit
Data width : 8 bit (ASCII code/ no distinction between upper case and lower case)
Parity : None
Stop bit length : 1 bit
Baud rate : 9600 bps
Adjustment function
Direct effectivity of numbers : When a number is transmitted after a command, an adjustment value can be directly set.
Data format
The format of the control signal transmitted from the user side controller is as described below.
STX (02Hex) is arranged at the time of communication start and ETX (03Hex) is arranged at the time of data transmission complete,
and ID, command and parameter are arranged in between. Data consists of ASCII type alphanumeric characters, and there is no
distinction between the upper case and the lower case.
Command processing
Command processing starts as soon as the command is entered.
ID shall be the two asterisks, "∗∗".
Confirmation of reception
The main microcomputer will make judgment to the command received, and if the command is judged to be an effective one,
processing will be executed. When the system is in the standby status for the next command after completion of the
processing, a reply to the received command is sent out. The data to be responded is a data in the upper case after deleting
the ID code from the received command.
When responding, ERR is sent back if the command is unknown, and XXX is sent back if the command itself is valid but
it cannot be processed because of its status.
Processing in the case of an error
If a communication error occurs between STX and ETX, processing of that command is stopped, and the reception buffer is cleared.
In the command reception process, the character string transmitted after the receipt of STX are continued to be stored in the register,
and by receipt of ETX, the character string sandwiched between STX and ETX is recognized as a command. If the prepared character
string storage buffer (24 bytes including STX, ID and ETX) is exceeded, a reply will not be sent out.
In the case of command only
[single function command]
When setting/adjustment data is accompanied
[setting/adjustment command]
STX ID Command ETX STX ID Command Parameter ETX
0x02 ∗∗ 0x03 0x02 ∗∗ 0x03
When setting/adjustment data is accompanied
Data transmitted by PC Reply data
STX ID Command Parameter ETX STX Command Parameter ETX
0x02 ∗∗ 0x03 0x02 0x03
In the case of command only
Data transmitted by PC Reply data
STX ID Command ETX STX Command ETX
0x02 ∗∗ 0x03 0x02 0x03
In the case of invalid command
Data transmitted by PC Reply data
STX ID Command ETX STX Command ETX
0x02 ∗∗ 0x03 0x02 ERR 0x03
In the case of a command not executable due to its status
Data transmitted by PC Reply data
STX ID Command ETX STX Command ETX
0x02 ∗∗ 0x03 0x02 XXX 0x03
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