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The MS120 implements 2 communications protocols: Our proprietary SPLatLink and the industry standard ModBus RTU Slave.
The board can communicate with a PC via the PC232 programming cable, using an RS232 (COM) port on the PC. If you want to build a system with multiple controllers all communicating with a single PC, you can use an RS485 adaptor on each controller and on the PC. Please contact us about suitable adaptors.
SPLatLink
SPLatLink is our proprietary protocol for communicating with a SPLat controller while it is running your SPLat Program.
With the SPLatLink protocol a PC is able to address and read out the following resources within the controller:
In addition, it can force a PermStore instruction.
The SPLatLink protocol consists of a number of different serial communications message that must be used and formatted according to certain rules. That is quite complicated. However, we have produced a software component that takes care of all that. The component is an ActiveX control called SLCom.ocx. With SLCom.ocx it is possible to write SPLatLink capable PC applications using a variety of programing languages. The component is documented elsewhere in the SPLat Knowledge Base.
SPLatLink is deprecated and not suggested for new designs.
ModBus RTU Slave
ModBus is a widely accepted industry standard protocol. In the MS120 we have implemented ModBus RTU slave mode. In the initial implementations the ModBus feature allows message lengths up to the ModBus limit of 255 bytes. This may be reduced in the future as we add new features and have to "take back" some of the memory. In practice a 64-byte message can transfer 57 bytes of data.
More information on ModBus.
The older MS12 did not have ModBus, only SPLatLink.
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