Data access with iseg items

The communication takes place about iseg items. An iseg item consists of an object, a value, the timestamp when the item was refreshed (read by isegHAL), the timestamp when the item changed its value and the quality for that value. The objects represent the fully qualified names of the data points from the connected hardware (hardware interface or virtual lines, crates and modules). That means such an object specifies the hierarchical sequence to address a specific data point in the connected system.

Every item is addressed with the fully qualified name.

A fully qualified name consists of up to four layers:

• system - system information
• line - hardware interface or virtual line (0..15)
• device - module (0..63), crate (1000, 2000..2015)
• channel - high voltage channels (0..63)

Items of the system layer come without any additional address coding and owns their item name only e.g. CycleCounter.

The other layers will be divided by a dot e.g. 0.1.2.VoltageSet.

The layer "line" can address up to 16 hardware interfaces or virtual lines of iseg master-slave crate systems e.g. an ECH24A as master and an ECH43A plus an ECH238 as slave crates.

The layer "device" addresses up to 64 HV modules and up to 16 crates.

The layer "channel" addressed up to 48 channels.

Example for such an object consisting of line.device.channel.item:

0.1.2.VoltageSet
line(0).module(1).channel(2).item

0.1000.Status
line(0).crate(0).item

2.63.47.CurrentMeasure
line(2).module(63).channel(47).CurrentMeasure