PLC Interfaces

Programmable Logic Controllers (PLCs) are used to control and monitor the SPEAR, injector, and beamline machine protection system (MPS), kickers, and MS1-BDBLK. In addition, they are used to monitor the personal protection system (PPS) and provide limited control, in combination with the control room foot pedal. They also provide camera screen and power control but without status readback. The logic in the PLCs is described and maintained elsewhere. This page describes the interface between the PLCs and the SPEAR control system.

For MPS, kicker, and MS1-BDBLK PLCs, communication with EPICS go through EtherNet/IP modules residing in the SPEAR MPS and MS1-BLBLK AB-1756 chasses in B118 and other chasses in B120 (beamline MPS) and B140 (injector MPS). To control and monitor the kickers (except timing), a special "bridge" PLC in the B118 chassis communicates with the EtherNet/IP module in the SPEAR Kicker AB-1788 FlexIO chassis, also in B118.

For PPS, communication with EPICS is direct to the Siemens S7 PLC via a NIC card in the same chassis. See this schematic. PPS EPICS displays are used in various procedures:

For camera control, communication with EPICS is direct to the CompactLogix PLC using the same protocol as the EtherNet/IP modules.

Records associated with the PLC interface include:

Tag lists (memory locations on the PLC) associated with EPICS records:

There are a handful of control records, most of which are binary open, close, reset, and enable requests. The only analog control points are the voltages for the kicker system. Kicker control is described in the Kicker Operations presentation by Chris Pappas and the Kicker Overview presentation by Jim Sebek. The kicker power supply system manager page is also a good reference.

The kicker voltages are calibrated so both the setpoint and readback are shown in kV on the EPICS kicker display. Nominal values as of Feb 2015:

Kicker Voltage Setpoint (kV)
K1 1.550
K2 1.352
K3 1.785


Contact: Stephanie Allison
Last Modified: Feb 27, 2015