Serial Control Commands - Promax MO-180 Manual De Usuario

If we cannot open the COM port and yet we believe that everything is properly
configured, we can do a ping from the MS-DOS command prompt (Windows Startup
menu -> Run -> cmd) to the IP address of the modulator. This will tell us whether the
MO-180 is really accessible through the Ethernet connection.
It might be the case that the modulator replies to a ping command but we are
unable to open the virtual COM port. It is worthwhile then to check whether this COM
port is being used by another programme. If not, a fallback plan consists in deleting the
COM port and starting from scratch.

4.13.3 Serial control commands

The virtual COM port created following the steps described in the previous
section can be used to remotely control the MO-180 using a computer. A suitable set of
remote control commands enables us to query and change most of the functionality of
the modulator using software that controls serial devices such as Windows
Hyperterminal.
There is a control protocol to synchronise command reception and validation. A
command must be sent once an XON (ASCII 0x11 in hexadecimal) character is
received from the modulator. When the modulator detects a complete command, it
sends an XOF (0x13) code and, once validated and executed, an ACK (0x06) or NAK
(0x15) is sent back to the remote controller.
In order to ensure an error-free communication between the computer and the
modulator connected over an Ethernet network, the port settings of the virtual serial
port are always the following:
Rate: 19200; Data bits: 8; Parity: None; Stop bits: 1; Flow control: None
The MO-180 accepts remote commands at any time as long as the instrument
is on. It is not necessary to put the MO-180 in a special remote control mode.
The communication protocol is as follows:
1) The MO-180 transmits an XON code (0x11) every second. This tells any device
that might be listening on the other side of the virtual serial connection that the
modulator is ready to receive data.
2) Control commands sent to the modulator have the following format:
a. Initial character "*" (0x2A).
b. Set of characters that form the command.
c. End character CR (carry return, 0x0D).
3) Once a command has been sent, an XOFF will be received, indicating that the
transmission of any new command must be held on until the current one is
completed.
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USER'S MANUAL MO-180
04/2008