CNC machine monitoring – data collection methods
CNC machine monitoring involves getting data from the machine about its status. This can be done in various ways, depending on the features available on the machine.
Method 1: Send out data through RS232 serial port using Macro calls
E.g., On Fanuc or Haas. Data is sent out through CNC machine’s serial port using the DPRNT command whenever there is a cycle start/end, spindle on/off, etc. Machine’s serial port is connected to a server via serial-to-LAN converters, over wired or WiFi network. Data is sent to the server, reports are visible on PCs on the local network.
1. Limited to CNC machines that have Fanuc Macro B option or equivalent.
2. Macro B (or equivalent) option costs money.
3. Requires IT infrastructure – cabling, serial or LAN hardware, server, IT personnel.
4. Long installation time because of LAN and RS232 port connections.
5. High capital cost and maintenance cost of network.
6. Requires macro calls to be inserted in every program. Does not work if people forget to insert these, or deliberately do not insert them.
7. High downtime because of variety of equipment involved – cabling, LAN hardware, server. If any of these fails, the system fails. It is also susceptible to sabotage because everything is in the open.
8. Mobility of machines is poor – to move machines within your shop, you’ll also have to rewire the serial connection from the machine and the LAN cabling from the machine to the server. Machine monitoring is down for the duration of this rewiring, which is typically a few days.
Method 2: Send out data through the machine’s ethernet port
E.g., with Fanuc Focas, OPC-UA on Siemens, MTConnect, Haas ethernet, Mitsubishi ethernet. Data is sent out through machine’s ethernet port. Machine’s ethernet port is connected to a server via serial-LAN converters, over wired or WiFi network on shop floor. Data is sent to the server, reports are visible on PCs on the local network, OR Data is sent to the Cloud, reports are visible on internet on PC, tablet or mobile phone.
1. Large variety of data can be acquired – spindle power, FRO status, spindle temperature, etc.
2. Requires machine to have ethernet communcation capability.
3. Long installation time for cabling and LAN infrastructure.
4. High capital cost and maintenance cost of network.
5. Limited to newer machines, typically after 2015.
6. Requires local IT infrastructure – cabling, LAN switches or WiFi access points, server/ internet router
7. Requires a team of IT personnel to maintain the IT infrastructure.
7. High downtime because of variety of equipment involved – cabling, LAN hardware, switches/access points, server, router.
8. Mobility of the system is poor – to move machines within your shop, you’ll also have to rewire the LAN connections to the machine. This can be improved by using WiFi LAN.
Method 3: Monitor status of signals at machine’s relays
This is done through a sensor that tracks digital signal lines from the CNC machine’s PLC. Send the data direct to the Cloud. Hardware sensor reads status of relays to determine cycle start/end, spindle on/off, etc. Sensor directly transmits data to Cloud via mobile phone network. Reports are visible on internet on PC, tablet or mobile phone.
1. Short installation time – 30 minutes typical.
2. No IT infrastructure required, and hence no IT maintenance.
3. No capital and recurring cost of IT infrastructure and maintenance.
4. Works only with machines that have signals on 24V digital outputs.
5. No downtime caused by IT equipment failure.
6. Cannot be sabotaged, because the sensor hardware sits inside the machine control panel with nothing coming outside.
7. Mobility of machines is very high. The sensor hardware moves with the machine, and starts tracking as soon as the machine is powered on in its new location.
8. Can only get on/off type of data – cycle start/ end, spindle start/stop, machine fault. Cannot get program number, feed rate override status, spindle temperature, etc.
Method 1 is the least preferred, for reasons of cost, installation time, and poor reliability. It is obsolete.
Method 2 gives the most data, but is limited to newer machines and involves LAN connections.
Method 3 involves the lowest cost and installation time and has the highest reliability, but cannot track machine internal parameters.
LEANworx Cloud Industry 4.0 is ideally suited for CNC machine monitoring. It supports both method 2 and method 3. Its grandfather (which was launched in 2005) used to support method 1.
Peepal trees – the ‘never give up’ trees
Walking under a flyover in Bangalore one hot afternoon, I saw this beautiful sight of a whole lot of vegetation growing from drain pipes that are meant to carry rain water off the road.
The pipes have mud deposited in them from the road and from airborne dust, and the open end of every pipe has a tree or plant growing. Most of these are peepal trees, and I there are a couple of ferns. There were even birds hanging around these little trees. Kind of like a little forest.
The peepal is an extremely hardy tree with beautiful heart shaped leaves, that even grows in cracks in walls. It just requires a bare minimum of nutrients and water to survive. In its natural state it grows up to 30 m. high with a trunk 3 m. in diameter. In constrained environments like these pipes, it gets naturally bonsai-fied.
The peepal is also known as the Bodhi tree, because the Buddha attained enlightenment while meditating under it, in Bodh Gaya in Bihar. It’s actually called Ficus Religiosa for this reason. Strictly speaking, only peepal trees that are direct descendents of the original tree in Bodh gaya can be called Bodhi trees. The peepal is a cousin of a whole lot of other Ficus varieties like the Banyan (Ficus benghalensis) and the tree that bears figs that we eat (Ficus carica).