The pickoff.sch schematic

Links from the schematic:

• devctlp.sch schematic
• assemblyControl record

A description of the operation of the assembly, and the algorithms used to determine the positions of the five pickoff mechanisms, is given in the documentation detailing the operation of the pickoff assembly DM screen.

The CAD and CAR records on this schematic are not used. They were included for compliance with Gemini interface standards that was eventually deemed not required on NAOMI.

Upon receipt of a "go" directive in INDEX mode, the assembly forwards named index positions to each of it's attached devices, in the sequence required to index the whole assembly adequately. These named positions are defined in the lookup tables for the devices, pox/poy/col/len/ccd_device.lut.

When performing a MOVE operation, the assembly examines input fields A, B, C, D and E for numerical values. These are the demanded positions for the pickoff X and Y stages, the fore-optics stage, lenslet wheel and CCD stages respectively. If a field contains a non-numerical string, the assembly attempts to locate the string in its list of allowed named positions. A number of different named positions are defined for each stage, as defined in the assembly lookup table, pick_assembly.lut. Details are given in the documentation detailing the operation of the pickoff assembly DM screen.

The various parameters and offsets needed to compute the target positions of each stage are defined using named parameters in the pickoff assemblyControl record lookup table.

The binary input record "ilck" is used to interlock the pickoff assembly. This (boolean) signal is forwarded, via a fanout record, to the assemblyControl (ILCK field) and deviceControl (FLT field) records. Upon receipt of a non-zero value at the FLT field, the devices will immediately stop all motion of the pickoff mechanisms. The assembly will stop any operation it is current engaged in. Normal operation can be resumed by restoring the interlock signal to its default (zero) value.