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aldas / modbus-tcp-client

PHP client for Modbus TCP and Modbus RTU over TCP (can be used for serial)
Apache License 2.0
194 stars 56 forks source link

New to modbus #24

Closed jamenlang closed 5 years ago

jamenlang commented 5 years ago

The project says this is a modbus client. Can I use it as a PLC emulator? I'd like to be able to poll data with SNMP and convert it to modbus acting as a PLC would.

server -> php: wait for modbus request -> get one, figure out what device it's for, -> poll the device for snmp data. -> convert snmp data to modbus coils registers... idk -> return response.

aldas commented 5 years ago

Well, you could use this library to respond modbus packets. I'm using this in tests see https://github.com/aldas/modbus-tcp-client/blob/master/tests/integration/Fc3ReadHoldingRegistersTest.php#L16

and server to respond data https://github.com/aldas/modbus-tcp-client/blob/6816336b8ebe6cc7d4c4f45f794386faaa5fd3ac/tests/integration/MockResponseServer.php#L45

so you could change pack('H*', $responsePacket) with (new ReadCoilsResponse($data))->__toString()

jamenlang commented 5 years ago

Do i need react for that?

aldas commented 5 years ago

well by default php is used to serve as http server but to act as a modbus server, you need something that runs your PHP as plain tcp"socket" server and accepts connections to which your code responds data (modbus packets). Instead of React you could use https://amphp.org/socket/ or roll your own server.

jamenlang commented 5 years ago

i understand now,

i installed amphp with composer i think.

composer require amphp/socket, i'm guessing react is installed the same way.

aldas commented 5 years ago

yep, see this https://github.com/reactphp/socket

jamenlang commented 5 years ago

looks like i'll have to install react datagram as well?

composer require react/datagram:^1.4

aldas commented 5 years ago

React Datagram (https://github.com/reactphp/datagram) is needed when you want to build modbus UDP server. If you want serve your requests over TCP you only need https://github.com/reactphp/socket