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J-Kem's KEM-Comm software can interface with up to 32 instruments simultaneously. The key to constructing a controller network is having the correct hardware to support the network. PC’s are equipped with a RS232 comm port (this is the male 9-pin connector on the back of the PC). The importance of this is that RS232 communications only support connection to ONE device. That means if the PC’s comm port is directly connected to J-KEM’s controller, it can only be connected to a single controller at any one time. |
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| For a PC to communicate with more than 1 controller, a RS485 network must be constructed This would be a simple task if PC’s had a RS485 port, but PC’s only have a RS232 port. J-KEM has made constructing a RS485 network straightforward and inexpensive. A network is constructed by attaching one end of a standard 9-pin serial cable to the PC’s normal comm port, then the other end to J-KEM’s “RS232 to 485 converter”. The outlet of the converter is a standard “phone jack” style receptacle. Connecting the converter to the first controller using RS485 cable forms the first connection. Subsequent connections (up to 32) are made by connecting RS485 cables from controller #1 to controller #2, then controller #2 to controller #3, etc. All connections are made by attaching RS485 cables from controller to controller, which is just like plugging a phone cord into a wall outlet. It should be noted that once a network is constructed, not all the controllers need to be on to collect data. If you only need to collect data from controllers #1 and #4, then only controllers #1 and #4 need to be on (controllers #2 and #3 can be off and the network still works). |
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