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<< Click to Display Table of Contents >> Connecting your scale to your computer |
  
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<< Click to Display Table of Contents >> Connecting your scale to your computer |
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If you want to acquire a scale weight directly from your scale (your Truck Scale for example), your scale must be connected to a digital weight indicator and the digital weight indicator must be connected to your computer.
Connecting the digital weight indicator to a serial port on your computer is the most common way to connect your scale to your computer.
Other connection methods include a using a direct Ethernet connection from your digital weight indicator to a router or network switch or using an Ethernet serial port server .
Of course once your scale is connected to your computer you will need software to read the data from the digital weight indicator.
Your digital weight indicator will look something like this:
M2000
Your indicator must be capable and configured to send weight data continuously (stream mode) or on request (demand mode).
Stream mode is the preferred mode and easiest to debug.
While your indicator may be capable of stream or demand mode, that doesn't mean that it either of those modes have been enabled. You may need to have a service technician configure your indicator to enable it to send data in stream or demand mode.
Your indicator should not be configured so that the scale operator has to manually cause the indicator to send data (e.g. by pressing the Print key on the indicator front panel).
If you are connecting a bench scale or a laboratory balance the digital weight indicator and scale are usually a self-contained unit.
The RS232 serial port remains the most common way to connect your digital weight indicator to your computer.
| 1. | The digital weight indicator must have an RS232 serial port that is compatible with the PC you are using. If it does not: |
| o | Make any necessary modifications required to add a serial port to your existing digital weight indicator. |
| o | Replace your digital weight indicator indicator with one that has an RS232 serial port. |
| 2. | The interface cable that connects the indicator to the computer is normally custom made and installed by your scale supplier or the service technician that maintains your scale. If your scale indicator has never been connected to a PC, contact the service provider that maintains your scale and ask them to have an interface cable made and installed. More often than not, the end that connects to the digital weight indicator is hardwired to a terminal block within the digital weight indicator. In the example below, the digital weight indicator has 2 serial ports labeled COM1 and COM2.  The end of the cable that connects to the computer should have a 9-position socket connector. |
9-position socket connector
Using the example and assuming the digital weight indicator transmitting data continuously, the terminal marked TX would be connected to pin 2 on the 9-position connector and the terminal labeled COM would be connected to pin 5.
If the indicator can only transmit data on request, the terminal labeled RX needs to be connected to pin 3.
| 3. | Last but not least, your PC will need RS232 serial port. The typical PC serial port is a 9-position pin connector socket connector. |
9-position pin connector
If you purchase an off the shelf desktop, laptop or notebook computer, there is very little chance that it will have a serial port that is accessible. You will need to purchase a USB-Serial adapter or serial port server.
The simplest choice is a USB-Serial adapter. Startech has an exceptional selection of USB-Serial adapters and we recommend the ICUSB232PRO adapter.
USB-Serial Adapter
Another alternative is a Ethernet-based serial port server. If the digital weight indicator is located more than 15 feet from the computer, the serial port server is a great choice. If you need to connect any more than 2 scales to your computer a serial port server is also an excellent choice.
Ethernet Serial Server
If you are having a PC custom built for you, ask the builder to install a serial port.
If you are unsure about any of the items listed above, contact us.
It is becoming more common digital weight indicators and electronic bench/platform/lab scales to support Ethernet.
If you are using Ethernet (either TCP or UDP), we will assume the indicator has an RJ45 connector and you can use generic off the shelf CAT5 or CAT6 cabling. Select the cable that is appropriate for your network hardware, connect one end to the indicator and one end to the switch or router and you're done.
If you must connect the indicator directly to your computer you may need a crossover cable or crossover adapter.
The critical part of the Ethernet configuration is assigning the indicator an IP address and port number. Then you need to make sure the indicator is on the same IP network as the PC and that the port number is available or your software will be unable to make a connection to the indicator.
You should always assign a static IP address to the indicator making sure it's valid for the network your PC is connected to and that it's not in the range that may be used by your networks DHCP server. Don't allow the indicator to be assigned an IP address by DHCP.