The B1a module is used in the SPI rack to operate modules initially designed for the IVVI rack. The B1a provide a front-side access on the SPI rack to signals whose connection in IVVI-intended modules is on the back-side. These signals may come from or feed into external instrumentation or other SPI modules. Often, they are analog signals controling the IVVI modules.
In addition the B1a can provide electrical isolation to some such signals between the control environment and the sample environment. Therefore connections through the B1a may be either:
Isolated in the B1a: This is meant for initially-non-isolated signals, such as those produced by external instruments (e.g. lock-ins) powered from the control room mains-fed power supply.
Non-isolated in the B1a: This is meant for already-isolated signal, such as produced by a D5a from an isolated-contrller SPI rack.
The B1a is meant for placement at specified locations within the SPI rack, where it can connect to a maximum of two neighboring modules (one on its left and another on its right). These two modules can be of different types - the combination can include source, measurement or source & measurement modules. Note that the number of connections available through the B1a is in fact 3 pairs, and not 2. Therefore it is possible to connect two pairs to one module, and one pair to the other module. It is not necessary to populate both neighboring modules, and some connections may not be in use. . For more information and examples, see the IVVI Compatibility page.
The routing of signals through the B1a is configurable, determined by hard wiring within the module:
The input signals into the left- and right-side neighboring modules can connect to their x1 or the x0.01 inputs. In some cases the 'In' signals (non-isolated, MCX) connect to the x1 inputs, while the ISO In signals (BNC) connect to the x0.01 inputs. In any case, a wiring diagram in the inner side of the module gives all details for independent re-wiring as needed.
The output signal can be fed from either the left- or right-side neighboring module. This is indicated on the module front-panel.
For SW-controlled isolated input connections. without an output connection, see the B1b module page. For 2 input pairs and 2 differential outputs, all non-isolated, see the B1c module page.