CNI RM85x, Руководство пользователя, Страница: 9 / 58

Installation
05-10-2007 CNI Engineering S.r.l.
1
1 Installation
Make the settings specified in the relevant
User Manual – Technical Specifications and
Connections
to ensure correct installation of the RM85x family of hand-held terminals.
2 Serial communication
The minimum size for a transmitted data packet size is 10 bits. These comprise
 1 start bit
 8 data bits
 1 stop bit
Start Data Stop
0 lsb Msb 1
Packet format is as follows:
1 start bit, 8 data bits, no parity, 1 stop bit
2.1 VT100 protocol
RM85x hand-held terminals support a sub-set of commands from the standard VT100 protocol as well
as customised commands for I/O control.
VT100 protocol includes the necessary XON/XOFF communication control. The terminal has a FIFO
buffer in reception and transmission comprising 64 characters.
If the content of the reception buffer reaches more than 48 characters, the terminal sends an XOFF
character (0x13) to the master to request it to stop transmitting as quickly as possible.
Once an XOFF character has been sent and the reception buffer has dropped below 16 characters
again, the terminal sends an XON character (0x11) to tell the master that it can start transmitting
again.
In the same way the master can also send the terminal an XOFF character when so required by its
own control logic. In this case, the terminal stops transmitting as quickly as possible and waits to
receive an XON character before restarting.
For further details on VT100 protocol, visit the following site: http://vt100.net
2.2 CNI proprietary protocol
2.2.1 Control characters
RM85x hand-held terminals send the remote controller commands and data requests in packets
containing a number of characters. Each packet starts with the STX control character and ends with
the ETX control character.
Packets do not normally contain other STX or ETX characters. If STX, ETX, ESC, XON or XOFF
characters have to be transmitted, these must first be split into two characters according to the
following table.