The X-SSI-2 module provides two SSI channels. The connected transducers are sampled simultaneously, and can then be read.
The number of bits per channel can be programmed between 2 and 32, as can the co-ding of the result (Gray code or binary). The clock rate can be programmed between 16.2 kHz and 8.25 MHz.
Warning: Some displacement transducers (e.g. Stegmann) need somewhat more time from the first clock edge before reading than is necessary for the following bits. In such cases the clock must match the longer period. Other displacement transducers include voltage monitoring, whose state is returned in a data bit. If this bit is set, the result is invalid. Gray coding is also possible with these transducers, since the status bit is transmitted in the MSB.
Each channel has its own differential clock output and a differential data input. Im-mediately after switching on the system, CLK+ is at log. 1, CLK- at log. 0. Both are connected to the logic section of the module via RS-422 drivers.
Two digital inputs and two digital outputs are also available.
These are also connected to the logic via RS-422 drivers.
The module also includes an on-board LED that can be switched by software.