CONNECTING MULTIPLE GIGE CAMERAS TO ONE ETHERNET PORT
How do I connect multiple GigE industrial cameras to a single network port?
We will explain how to connect 4 industrial GigE cameras. Therefore we have used the following material:
4x MER-630-16GC-P, 6.3MP industrial GigE camera
5 Port PoE switch 1000mbit / 1Gbit
PC with windows 10 and a 1000mbit / 1Gbit networkcard
Please double check that your connection is 1000mbit / 1Gbit and not 100mbit. Some PoE switches are only 100mbit and we see more often that customer think they have 1Gbit connection but in reality they have a 100mbit connection. This article explains how you can check if you have a 1 Gbit connection. You can only check this when the industrial GigE camera is connected.
Step 1, connect all GigE cameras to the PoE switch
Connect the GigE cameras to the PoE switch and check if the LED on the back of the camera is on. This means that the camera is receiving power from the PoE switch.
Step 2, program correct IP address for each GigE camera
Every GigE industrial camera needs his own IP address. An example structure would be: - Camera 1 -> 192.168.0.51 - Camera 2 -> 192.168.0.52 - Camera 3 -> 192.168.0.53 - Camera 4 -> 192.168.0.54 In step 1 and 2 of this articlewe explain how you can program the IP addresses of every camera using the GigE IP configutor that is installed with our SDK
Step 3, calculate the packetsize and package delay.
The packetsize and packetdelay are parameters to control the bandwidth of an industrial GigE camera. When connecting multiple cameras to one system we have to reduce the bandwidth of every camera, to make sure images are transferred stable from the camera to the PC. Incorrect parameters will cause no images or incomplete images.
Max bandwidth for each camera
• The PC network card needs 10% of its bandwidth reserved for packet retransmission, so you can use 90% of 1 Gbps for data transfer. • 1 Gbps = 1000 Mbit/s = 125 Mbyte/sec • Available bandwidth is 125 Mbyte/sec * 0.9 (90% bandwidth) = 112,5 Mbyte/sec • With 4 cameras, the maximum bandwidth you can allocate for each camera will be 112.5 Mbyte/s /4= 28.1 Mbyte/sec per camera • With a resolution of 6.3Mpixel per camera, each camera can have a max frame-rate of: 28.1 (max bandwidth available per camera ) / 6.3Mpixel (resolution of camera) = 4,46fps
Defining values packet size (GevSCPS) and packet delay (GevSCPD)
When you have installed the Daheng Imaging SDK, you open the frame-rate calculator that is located at C:\Program Files\Daheng Imaging\GalaxySDK\Doc
In the framerate calculator excel file, go to the tab with you camera type (MER-630 in our case)
Change the excel value of the exposure time to 100
Change the excel value of the GevSCPD to 8000
Change the excel value of the GevSCPSPacketSize to a value so that the framerate is below 4,46fps. The max value is 8192.
If you used the max value for GevSCPSPacketSize but as a result the framerate is much lower than the max frame-rate, you need to lower the value of GevSCPD so that the framerate increases just to below the max framerate (in our case 4,46fps)
Step 4, programming the packetsize and package delay
The calculated values have to be programmed in each industrial camera connected to our switch. In step 3 of this articlewe explain how to do this.
Step 5, remarks when connecting multiple industrial cameras to one pc
When connecting many high resolution cameras to a single networkport, it may occur that the GevSCPD has a value higher than 1000. In that case, you have to increase the packetdelaytimeout, otherwise the industrial camera is not able to transfer the images on time to the pc, resulting in incomplete frames.