How to Ensure Your Cells Are Talking to Each Other
Posted on Nov 27, 2017 7:00 AM
Robot's not talking to each other. Families not talking to each other. It must be the festive season!
Communication is tricky at this time of year. During the festive period you want everyone to be on good speaking terms, but that can be asking the impossible, can't it? Families are forced to spend more time together in one week than they have over the whole past year. There's a high risk of communication failures.
Your sisters have stopped talking to each other. Your parents are snapping at each other. Your grandmother has fallen out with the next door neighbor who — for some unknown reason — still pops in every three hours just to continue the argument. You and the cat are not on speaking terms since it stuck its claws in your ankle when someone pulled a Christmas cracker.
Sometimes you wish that the holiday would just finish. Then, you could get back to work on your production process where communication always works perfectly… or does it?
Just like a festive dinner table, things start to go wrong when cells don't talk to each other.
5 Signs That Cells Aren't Talking Talk to Each Other
Cells that aren't talking properly can wreak havoc on your production process. For example, you might see:
1. Low Production Figures
The first effect you might notice is a drop in production. This is usually a sign that something in the process is not working properly and suggests that further investigation is needed.
2. Build Up of Work in Progress
When you start looking closer at the problem, you may see piles of work in progress building up at certain stages of the process. This can help you to locate the source of the problem.
3. Everything Getting Out of Sync
Getting out of sync is the root of many communication problems, just as it is in your family meal! When your eight year old niece eats a whole box of chocolates and starts running around the house at 200 miles per hour, she's out of sync with everyone else — the adults are all collapsed with hunger because the meal is three hours late. When the food does finally arrive, the adults are all angry and your niece is crashed out on the floor after her sugar rush.
When your production cells get out of sync, the whole process starts to suffer.
4. Lots of Reworking
Another sign that things are not working properly is when products are faulty and require a lot of reworking. This can happen, for example, when cells don't communicate accurate details of the product to the following cell.
The festive season is full of complaints: "I don't like turkey!" and "I only like turkey!" and "I would like turkey but I can't have any because grandad ate it all!"
Complaints are often a warning sign of failures of communication. In business, these complaints might come from customers — if the failures have caused delays or defects — or from team members working in other cells who can't do their jobs properly as a result of the failures.
How to Tell If Your Robots Aren't Talking
Good communication is vital for any production process, but it's especially important when you are using robots. Unlike fully manual processes, robots can't tell you when something is going wrong… or can they?
Well actually, now they can! With robot monitoring software, like Insights, you can monitor the productivity of your robot in real time.
But, what are the signs that robots are not talking to each other?
The Two Types of Robot Communication
Two methods of robot-robot communication are used for most of the setups we see at Robotiq. Let's imagine connecting two robots called Anja and Norman.
- Via Discrete I/O — In this case, one-way communication is achieved via general purpose Digital I/O (DI input or DO output). For Anja to send information to Norman we could connect Anja's DO4 to Norman's DI7, for example. For two way-communication, we would have to connect Norman's DO6 to Anja's DI7, for example. This is a very basic form of communication as it can only send an on/off signal, but it can be useful in some situations.
- Via Communication Protocol — The most common way to communicate between robots is via an Ethernet-based communication protocol, like Modbus, Ethernet/IP or Profinet. It is more flexible than Discrete I/O and allows for more complex communication. One robot, Anja for example, is set as the Master and Norman is set as the Client. To send information, Anja can write to a register — called AJ_Reg1 for example — and Norman can read this register. To send information back, Norman could write to another register — called NR_Reg1 — which Anja could read. Information can either be sent as a number or as an on/off signal.
When there seems to be a breakdown of communication between the two robots, robot monitoring software helps you to troubleshoot.
3 Common Signs That Robot Communication Has Failed
In Insights, a failure in communication will show up differently depending on the communication method you are using.
Three common signs that robots have stopped talking to each other are:
- Lack of Signal Change for Discrete I/O — When you are using Discrete I/O, you can view the state of the Digital Inputs directly in the Insights interface for each robot. This makes it straightforward to debug. Imagine Anja assembles a motor and Norman performs a quality check immediately afterward. When Anja has finished her task she sends a High signal to Norman via the Digital I/O. If you see in Insights that Norman never receives that signal, you can deduce that the problem is within the connection between the robots.
- Waiting … — Wait time is a particularly important metric within Insights. It allows you to detect when the robot is stopped and waiting for some other process to complete. Many breakdowns in communication present themselves as unusually long wait times. For example, imagine you are using Modbus communication and Anja is waiting for Norman to write to a register called ObjectReceivedReg before she begins the next assembly cycle. If there is a breakdown in communication, the register will never change and Anja will wait indefinitely.
- Robots Offline — Sometimes a robot will not only lose communication with the other robot cells, it will also lose communication with the whole network. This will be visible as a "Disconnected" signal. You can configure Insights to automatically send an SMS message to your phone whenever this happens, meaning that you can start solving the problem immediately.
Once You've Found the Problem… Debug!
Detecting the root of communication problems is only the start. Just like when your family is having a festive argument, first you need to find out why people are unhappy then you have to work to find a solution that everyone agrees on.
Once you have identified that communication is the issue with your robot, use Insights and your own problem solving abilities to work towards a solution.
You can try a free demo of the Insights platform right now! It uses data from our Insights Demo robot. Just go to insights.robotiq.com