Chapter 4
Interfacing to Your Round Card
80188EB-Based Fieldbus Round Card User Manual
4-2
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National Instruments Corporation
DOUT pin is the Transmit pin and the DIN pin is the Receive pin
of serial port 1. Both of these pins provide 3 V compatible signals.
You can use this port as a debugger port to debug your application.
To interface to the COM ports on a host PC computer running a
debugger, you should provide means to convert these Fieldbus
signals to RS-232 format.
Using the Software
Overview
Most of the code that will be running on your Fieldbus Round Card has
already been written for you. It includes the Fieldbus protocol stack,
Function Block Shell, and Serial Driver, which are provided in the form
of a linkable library with your Fieldbus Round Card Interface Kit. This
library provides Fieldbus communications and an API (the Function
Block Shell) designed to isolate your application as much as possible
from the specifics of the Fieldbus. For more specific information about
the Function Block Shell API, consult the NI-FBUS Function Block
Shell Reference Manual.
In addition, the library contains an API to allow HART or direct serial
access to the Round Card’s serial port. This API facilitates
communications with a HART or serial transducer external to the
Round Card. This Serial Driver API is also described in Chapter 8,
Serial Functions, of the NI-FBUS Function Block Shell Reference
Manual.
Developing Your Round Card Application
Complete the following steps to develop your application, after you
have installed the hardware and software:
1.
Write a device template for your device.
2.
Convert the device template to C code using the Device Code
Generator.
3.
Write your Function Block Callbacks, algorithms, and device
interface code.
4.
Write your
userStart
function to register your callbacks.
5.
Write your Device Configuration.
6.
Convert your Device Configuration to C code using the
Configuration Code Generator.
