问题
I would like to be able to develop an iPhone application that can communicate with Modbus devices, but I'm not sure how to proceed. Has anyone had experience with this or are there existing libraries out there for this purpose?
回答1:
You will need first to know how to make a simple TCP client on your iPhone, and a simple TCP server on your computer that your iPhone client will talk to via WiFi. Make sure PING command works and firewall does not block your server port before any client/server experiments, and make sure that server port for experimenting is greater then 1024 and not already used. Then take a look at MODBUS TCP specification from official site, get familiar with function codes you are interested in, and study C code found here. Then make a simple MODBUS TCP client that can send a request to MODBUS TCP server and interprete an answer. The best way is to start reading single register value, then progress in time and add more functions.
回答2:
I do exactly all above points, my iOS Modbus lib works fine, application is now up on AppStore, PLCLink read and set any modBus data into my Wago home automation. Installation guide : http://pautex.fr/plclink
来源：https://stackoverflow.com/questions/3652140/how-do-you-communicate-to-a-modbus-device-within-an-iphone-application