PLC Interfaces

Programmable Logic Controllers (PLCs) are used to control and monitor the SPEAR, injector, booster RF SSA, and beamline machine protection system (MPS), SPEAR and booster kickers, MS1-BDBLK bend dipole bulk power supply, and booster RF circulator control. 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, other chasses in B120 (beamline MPS), and B140 (injector MPS, booster RF, and booster kickers). To control and monitor the SPEAR 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 and booster RF SSA MPS, 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 SPEAR kicker system. SPEAR kicker control is described in the Kicker Operations presentation by Chris Pappas and the Kicker Overview presentation by Jim Sebek. The SPEAR kicker power supply system manager page is also a good reference. The booster kicker control is described in the Booster Kicker Upgrade presentation by Fernando Rafael.

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

SPEAR Kicker Voltage Setpoint (kV)
K1 1.547
K2 1.379
K3 1.714


Contact: Stephanie Allison
Last Modified: Apr 1, 2016