Gilderfluke&Co Frequency Shift Keyed/Remote Terminal Unit - Manual (Page 13)

FSK/RTU CONFIGURATION:
All commands sent to the FSK/RTU Unit through its serial interface take the following format. All charac-
ters are sent in ASCII. All numeric values are sent in HEXadecimal (HEX for short), and consist of one or
more ASCII characters (0-9, A through F). The case (as in upper and lower) of all input is important. A lower
case 'a' signifies a command, while an 'A' is a numeric value. If the FSK/RTU Unit receives another com-
mand while it is waiting for additional input needed to complete the previous command, it will abandon
the previous command and start working on the new one.
To communicate with the FSK/RTU Unit through the serial port, you can use just about any computer or
terminal which has a serial port on it. Some newer computer designs, like the Apple Macintosh, come with
serial ports which are directly compatible with the RS-422 / RS-485 signal levels the FSK/RTU Unit wants to
see. These signal levels are close enough to be used with the RS-232 signal levels found on most older
computers (like most IBMs and compatibles) with only a simple adapter cable, so long as the wire isn't too
long. To gain the full advantage of the RS-422 / RS-485 signal levels you will need to use a signal level
adapter like our 232conv-09.
If you are using a computer as a terminal you will need to run a modem or terminal emulation pro-
gram. These will send everything you type on the keyboard out the serial port on your computer while
printing on the screen anything which comes in from the FSK/RTU Unit through the serial port. Every copy
of Windows comes with TERM.EXE, which is just such a program. A modem program will usually have the
advantage over a terminal emulation program in that it will allow you to save data to your computer's disk
drives and then send it back to the FSK/RTU Unit at a later date. The FSK/RTU Unit uses no screen control
codes or ESCape sequences, so it should work on any machine with an 80 column by 24 line display.
Machines with other display formats will work, but may not look so neat on the screen.
When configuring your modem program, you should set it for 9600 baud, 8 data bits, one stop bit,
and no parity. Higher or lower baud rates can be used if you configure the FSK/RTU Units’ serial port to run
at a different speed. You should set your program not to insert an extra LineFeed (LF) character after each
Carriage Return (CR) it receives. If you are going to be downloading configuration strings to the system
(command ‘s’), you will also need to tell the modem program to put a slight delay between each charac-
ter sent in order to not over run the FSK/RTU Unit’s incoming data buffer.
If you have hooked up the FSK/RTU Unit to your computer and it still doesn’t seem to respond to the
keyboard, the first thing to check is that you are attached to the right serial port. The easiest way to do this
is to disconnect the FSK/RTU Unit and short between the Tx data out and Rx data in pins on the serial port
connector on the back of your computer. On all IBMs and compatibles this means sticking a paper clip or
similar tool between pins 2 and 3 on the ‘Com.’ connector. While still running the modem program, any-
thing you type should be shown on the screen while this paper clip is in place, while nothing will appear
when you remove it. If your computer passes this test, then you are using the right serial port and the
problem is most likely the baud rate setting or in your wiring to the FSK/RTU Unit. If you get characters on
the screen even with the paper clip removed from the serial port, it means you probably need to set the
‘echo’ mode to ‘none’ or ‘full duplex’ and try this test again.
The serial data signals from the FSK/RTU Unit are brought out on a 6 position RJ-11 (modular telephone
style connector). Facing the end of the cable with the release latch upwards, its pin out is as follows:
G ILDERFLUKE & C O . • 205 S OUTH F LOWER S T . • B URBANK , C ALIF . 91502-2102 • 818/840-9484 • FAX 818/840-9485
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