I am designing an HMI for a diesel generator set that uses J1939. This generator set has a load bank that is operated by a PLC. I want to have the PLC put the load bank status onto the J1939 bus. I'm looking through J1939 but I can't find a PGN for a load bank- is it called something other than "load bank" or am I looking at creating a custom PGN
Thanks
Matt
Related
I need to add a chat in my application to let users contact each others.
Requirements
only 1 to 1 communication customer 2 customer (no group or chat room)
essentially text, image upload is a bonus (probably as a second step)
message must be delivered in a reasonable delay (maybe ... 20 sec max)
max load: 3M chat msg / days,
Protocol / API
I only have way back memories from the university and the TCP sockets, a recent trial to gRPC & protocol buffers but none of these looks like a good fit.
Web Socket ?
Then, I've found some articles about the Web Socket protocol and an implementation in Go from the Gorilla team and the Web Socket API from MDN
HTTP/3 ?
WebTransport session, bidirectional stream
Caddy HTTP/3 server or an implementation of Web Transport from Marten Seemann based on quic-go
I also take a look at nsq but it looks like a Rube Goldberg machine in this context.
PubSub API
Google provides a PubSub API that can be connected to BigQuery and Dataflow
Persistence ... ?
Cassandra or MongoDB look like good options here...
Firebase Realtime database / Firestore? Advantage here is to abstract a lot of complexity, we just send data and subscribe to updates. Not sure about the cost efficiency vs the other solutions.
A complete solution has been given by minghsu0107 here: go-random-chat...I'm not skilled enough to have any thought on this architecture. The only thing I'm thinking about is that this solution is maintained by a single person ... which mean if I chose to use it, I must be able to understand every single piece of it. So if someone could just set me on the "right" path, or at least to move me away from the "wrong" ones before I spend weeks on these concepts, that'd be awesome :D
Given the background you've supplied, I think you'd be better off integrating an open-source, off-the-shelf messaging plugin, rather than trying to build your own.
Something like Rocket or Zulip might suit (and save you a lot of grief).
I am the author of go-random-chat. The main difference between 1-to-1 and group chat is that the message status in 1-to-1 chat is either seen or unseen, whereas in group chat it's a counter to record the number of users that have seen the message. Therefore, you can still refer to those Slack-like implementations besides go-random-chat to see how messaging works under the hood.
This is probably not the right forum to ask this, but I need to program a Phoenix Contact PLC in Structured Text. The PLC should communicate with a motor that uses CANOpen protocol. The only resource I have is the dbc file. I'm kinda lost about where to start. If you have some suggestions/recommendations I would appreciate it.
Implementing a CANopen stack can be very time consuming and complex but make a node working with your soft can be easy depending on the slave you have to control.
A good tip would be first to connect the motor to CAN viewer like PCAN View or whatever depending on hardware you have.
First step is to send the start message at adress 0x000 DLC:2, Data 01 00 to start all slave or 01 motor node id to start only the motor.
This will force the motor to start in operational mode and you will be able to see if it send something or not.
You should probably see a heartbeat message with ID: 700+node id and maybe some PDO with a the current speed, temperature or whatever (the motor documentation should help you better understand what the motor send and wait).
In this case in your soft you would have to implement the start message sending if no heartbeat or heartbeat value different than 0x05 (means operational), the PDO read if there is one and a PDO control command which give to the motor the speed needed (you should find the message in the motor documentation)
There might be some other needs like SDO parametrization but worth to try with these few steps before
Please let me know I can help you
I have already developed a Clinic management application for Allergy Control Clinics which stores patients' medical files and test results in a database and generates reports for analysis.
there's a section for storing spirometry results in the database. currently i get results
from an Excel file which is exported by WinspiroPro (the application that comes with spirolab devices) and store them in the database.
few days ago i came across the word "HL7" which seems to be a Standard protocol for communicating with these medical devices, so i can directly get the results from the device using Delphi.
also in spirolab device user manual it is mentioned that the device is compatible with this system.
now my question is, how can I implement this system (HL7) in delphi?
Thanks
As is usual with these kind of inter-professional standards, you need to pay to get them, at least on http://www.hl7.org in this case.
If I search around on the net, there may be existing tools that you can use, or have a look how they work internally:
http://code.ohloh.net/search?s=HL7
https://code.google.com/hosting/search?q=HL7&sa=Search
http://sourceforge.net/directory/?q=HL7
HL7 is not bound to a specific transport layer. It is a protocol on the application level, the seventh layer of the ISO 7-layer-model, hence Level 7. It describes messages and the events, when this messages should be send.
It just gives some recommendations how to do message transfer on the subjacent layers, e.g. MLLP with tcp socket communication. But in principle you are free to use any transport layers you want, may it be direct socket communication, file transfer or what ever.
Although most systems now can use tcp, it is also possible to use HL7 with different underlying transport protocols as RS232. If I remember right, there was also an example about message transfer / coupling with RS232 in the implementation guides of the documentation. And yes, the documentation and protocol standard documetation is free after registering.
Did you ask your provider for the WinspiroPRO version with HL7 ability? Maybe it supports already socket communication with tcp.
Otherwise you either need access to the sourcecode of ldTCPCClient and replace the tcp part with an RS232 part or you have to use a software just for parsing/building (unmarshalling/marshalling) of HL7 messages together with a software, that handles the transportation level.
By the way, just from the name, I guess that ldTCPclient is not apt for your need, as you will probably need a host and not a client component.
I am writing a program to transfer files through a lan computers, it's been a while I'm searching for file transferring methods in Delphi. I found UDP is a good solution, but there is a problem: in every example or article I found there was a client program beside a server program, but my program have to send and receive to/from every computer in network, there is no specific server or client, something like p2p, I don't want to make a computer Server and another one Client, what should I do? I searched Indy articles too, it's working in Server/Client mode too (as far as I found).
UDP can work in broadcast mode, which is what you need. But such UDP broadcasts are not routable outside the current network (i.e. they are blocked by routers), so you have to implement something more complex if your project needs to be accessible outside the primary physical network.
Do not reinvent the wheel! If you want to see some working source implementing this concept, see Ares Galaxy:
"Delphi self-organizing p2p network project featuring high scale
capability and fast broadcast-type search system. Client supports
multi-source file transfers, partial file sharing, built-in
audio/video player and decentralized chat rooms".
The source code files are available from SourceForge. You could re-use/adapt the P2P network layer for your needs - but take attention to the license terms of Ares source code, if you use it in your projects.
Have a look at Indy's TIdTrivialFTP and TIdTrivialFTPServer components. TFTP is a UDP-based file transfer protocol.
We intend to design a system with three "tiers".
HQ, with a single server
lots of "nodes" on a regional basis
users, with iPads.
HQ communicates 2-way with the nodes which communciate 2-way with the users. Users never communicate with HQ nor vice-versa.
The powers that be decree a Windows app from HQ (using Delphi) and a native desktop app for the users' iPads. They have no opinion on the nodes.
If there are compelling technical arguments, I might be able to beat them down from "decree" to "prefer" on the Windows program (and, for isntance, make it browser based). The nodes have no GUI, they just sit there playing middle-man.
What's the best way for these things to communicate (SOAP/HTTP/AJAX/jQuery/home-brewed-protocol-on-top-of-TCP/something-else?) Is it best to use the same protocol end to end, or different protocols for hq<-->node and node<-->iPad?
Both ends of each of those two interfaces might wish to initiate a transaction (which I can easily do if I roll my own protocol), so should I use push/pull/long-poll or what?
I hope that this description makes sense. Please ask questions if it does not. Thanks.
Update:
File size is typcially below 1MB with nothing likely to be above 10MB or even 5MB. No second file will be sent before a first file is acknowledged.
Files flow "downhill" from HQ to node to iPad. Files will never flow "uphill", but there will be some small packets of data (in addition to acks) which are initiated by user action on the iPad. These will go to the local node and then to the HQ. We are probably talking <128 bytes.
I suppose there will also be general control & maintenance traffic at a low rate, in all directions.
For push / pull (publish / subscribe or peer to peer communication), cross-platform message brokers could be used. I am not sure if there are (iOS) client libraries for Microsoft Message Queue (MSMQ), but I would also evaluate open source solutions like HornetQ, Apache ActiveMQ, Apollo, OpenMQ, Apache QPid or RabbitMQ.
All these solutions provide a reliable foundation for distributed messaging, like failover, clustering, persistence, with high performance and many clients attached. On this infrastructure message with any content type (JSON, binary, plain text) can be exchanged, and on top messages can contain routing and priority information. They also support transacted messaging.
There are Delphi and Free Pascal client libraries available for many enterprise quality open source messaging products. (I am am the author of some of them, supporting ActiveMQ, Apollo, HornetQ, OpenMQ and RabbitMQ)
Check out MessagePack: http://msgpack.org/
Also, here's more RPC discussion on SO:
RPC frameworks available?
MessagePack: fast cross-platform serializer and RPC - please share experience
ICE might be of interest to you: http://zeroc.com/index.html
They have an iOS layer: http://zeroc.com/icetouch/index.html
IMHO there are too little requisites to decide what technology to use. What data are exchanged, how often, what size? Are there request/response time constraints? etc. etc. Never start selecting a technology before you understand your needs deeply.