Gasboy FMS KE200 - Manual (Page 11)

MDE-4465A KE200 Key Encoder/Maintenance Terminal Operation Manual · October 2007 Page 5
Communications System Overview
Communications
Communications Ports
The KE200 has two asynchronous ports to connect a logger printer and/or a data terminal. The
connection can be made by a direct cable or via a telephone modem. Ports 1 and 2 can be set to
a variety of baud rates (300, 600, 1200, 2400, 4800, and 9600) depending on the equipment
being connected.
• Port 1 is an RS-232/RS-422 port used to connect to external devices such as a PC, CRT or
external modem.
• Port 2 is an RS-232 port used to directly connect a printer (logger) to the KE200.
• A third port is also available for use with a built-in 1200/2400 baud modem (optional).
The cable length from the RS-232 port to the device is limited to 100 feet. If the distance
exceeds 100 feet, a Gasboy Short Haul Modem (P/N C05618) is required.
Communication Protocol
Devices that communicate with the KE200 must be able to transmit and receive full duplex,
ASCII, asynchronous data via an EIA RS-232 connection.
The KE200 uses a simple terminal protocol. No special characters are transmitted to designate
the beginning or end of the data blocks. Data is transmitted in serial bit format per character, as
follows:
One start bit, eight data bits, one stop bit.
Each character is echoed back to the transmitting device. This checks the integrity and enables
CRT operators to display transmitted data.
When used with the computer (or host) mode interface, the host computer initiates all
communications between itself and the KE200, with command packets. The KE200 responds
to the host command packets with response packets. All data exchanged between the KE200
and the host computer is packaged as a data packet.
KE200 Switch Settings
An 8-position switch bank, located on the KE200 CPU board is used to set the poll address and
the communications mode for the KE200. On switch bank SW1, for SW1-1 through SW1-4,
set the poll address when the Computer Mode interface is active. SW1-5 indicates the
communications mode for the KE200's Port 1. The last three switch positions (SW1-6 through
SW1-8) are currently unused. All switch settings are read during program initialization, at
power-up. If changes are made, the KE200 must be turned off then on, to recognize them.