Remote Control Through Rs-232 Interface - Promax MO-170 Manual De Instrucciones

4.9 REMOTE control through RS-232 interface

The MO-170 has an RS-232C compatible serial port to connect to a computer for
remote control. A suitable set of remote control commands allows enquiring and
changing any functional parameter.
Communication details: There is a control protocol to synchronize command
reception and validation. A command must be sent once an XON (coded 0x11:
hexadecimal value 11 or 17 in decimal) character is received from the instrument. When
the instrument detects a complete command, it sends an XOFF (0x13) code and, once
validated and executed, an ACK (0x06) or NAK (0x15) code is sent to the remote
controller.
To ensure error-free communication between the two devices, the communication
parameters for the serial port on the remote controller are as follows:
Rate: 19200 bauds, Data bits: 8 bits, Parity: None, Stop bits: 1
The MO-170 accepts remote commands at any time, when the instrument is on.
It's not necessary to put the instrument in a special remote control mode. The
communication is carried out using the transmitter and receiver data lines on the serial
port. Also the control signals CTS and RTS must be connected.
A standard PC computer DB9F to DB9F NULL MODEM serial cable can be used
when connecting the instrument to an available COM port.
The communication protocol is as follows:
1) MO-170 transmits a XON code (0x11) every second. The aim is to indicate to any
possible remote device that the equipment is ready to receive data.
2) At this moment, data streams can be sent to it. Each data stream is made of:
• Initial character '∗' (code 0x2A)
• Set of characters that describe data message.
• Final character CR (carry return, code 0x0D)
3) Once a data stream has been sent, an XOFF will be received, indicating that the
transmission of any new command must wait until completion of the current one.
4) Next, if the message format is correct and its execution has no errors, an ACK
(acknowledge) should be expected. Otherwise, an NAK (not acknowledge) will be
received.
5) If the sent message requires an answer, it will be sent at this point.
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USER'S MANUAL. MO-170
12/2006