Advantech ADAM-4500, Руководство пользователя

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RS-485 Connection
The RS-485 standard supports half-duplex communication. This means that just two wires are needed to
both transmit and receive data. Handshaking signals (such as RTS, Request To Send) are normally used
to control the direction of the data flow. A special I/O circuit in the ADAM-4500 automatically senses the
direction of the data flow and switches the transmission direction. No handshaking signals are necessary.
This RS-485 control is completely transparent to the user.
We recommend that shielded twisted-pair cables complying with the EIA RS-485 standard be used in the
network to reduce interference. Only one set of twisted-pair cables is required to transmit both Data and
RTS signals. We advise use of the following standard colors for the communication cables.
DATA + Yellow
DATA - Green
Chapter 3 Programming and Downloading
This chapter explains how to program applications and download programs into the ADAM-4500
controller. Additionally, it points out limitations and concerns of which you should be aware.
3.1 Programming
The operating system of ADAM-4500 is ROM-DOS, an MS-DOS equivalent system. It allows users to run
application programs written in assembly language as well as high level languages such as C or C++.
However, there are limitations when running application programs in the ADAM-4500. In order to build
successful applications, you should keep the following limitations and concerns in mind.
Mini BIOS Functions
The ADAM-4500 provides only two serial communication ports for connecting peripherals, so the mini
BIOS of ADAM-4500 only provides 10 function calls. Since the user's program can not use other BIOS
function calls, the ADAM-4500 may not work as intended. Additionally, certain language compilers such
as QBASIC directly call BIOS functions that are not executable in ADAM-4500. The ADAM-4500 mini
BIOS function calls are listed in the following table.
Function Subfunction
Task
07h 186 or greater co-processor esc instruct
10h 0eh TTY Clear output
11h Get equipment
12h Get memory size
15h 87h Extended memory read
88h Extended memory size
c0h PS/2 or AT style A20 Gate table
16h 0 Read TTY char
1 Get TTY status
2 Get TTY flags
18h Print "Failed to BOOT ROM-DOS" message
19h Reboot system
1ah 0 Get tick count
1 Set tick count
2 Get real time clock
3 Set real time clock
4 Get date
5 Set date
1ch Timer tick