QPC Alternate Databases

Table of contents

• streamDevice Support
  • Using the iocsh Script (Recommended)
  • Database Macro Reference
  • Protocol Files
  • Records Created
  • Setpoint Notes
  • Manual st.cmd: TCP Configuration
  • Manual st.cmd: Serial Configuration (via Moxa Terminal Server)
• Modbus Support
  • Macro Reference
  • Example: Modbus Configuration
• GUI Displays
  • QPCsingle_pump_streams.adl
  • QPCpumps_streams.adl
• Comparing the digitel Record and streamDevice Implementations
  • Protocol Differences
  • Setpoint Commands
  • Feature Comparison
  • Architecture
  • When to Use Which

In addition to the digitel record support, the QPC can be controlled using standard EPICS records through streamDevice or Modbus databases. These provide an alternative approach that does not require the custom digitel record type.

Each database creates records for a single pump supply on the QPC. Load one instance per pump.

streamDevice Support

The QPCstreams.db database uses streamDevice with protocol files for either serial or TCP communication. It provides records for current, pressure, voltage, status, HV enable/disable, model, firmware version, pressure units, pump size, setpoint on/off pressures, setpoint status, and pump name.

Using the iocsh Script (Recommended)

The QPCpump.iocsh script handles protocol file selection and database loading. Create the ASYN port first, then call the script once per pump:

# QPC via direct TCP to QPCe (port 23)
drvAsynIPPortConfigure("QPC1", "192.168.1.100:23", 0, 0, 0)
iocshLoad("$(VAC)/iocsh/QPCpump.iocsh", "PREFIX=SR:, INSTANCE=IP1, PORT=QPC1, SPLY=1, COMM=tcp")
iocshLoad("$(VAC)/iocsh/QPCpump.iocsh", "PREFIX=SR:, INSTANCE=IP2, PORT=QPC1, SPLY=2, COMM=tcp")
iocshLoad("$(VAC)/iocsh/QPCpump.iocsh", "PREFIX=SR:, INSTANCE=IP3, PORT=QPC1, SPLY=3, COMM=tcp")
iocshLoad("$(VAC)/iocsh/QPCpump.iocsh", "PREFIX=SR:, INSTANCE=IP4, PORT=QPC1, SPLY=4, COMM=tcp")

# QPC via serial over Moxa terminal server (COMM defaults to serial)
drvAsynIPPortConfigure("QPC1_ser", "10.6.33.133:4002", 0, 0, 0)
iocshLoad("$(VAC)/iocsh/QPCpump.iocsh", "PREFIX=SR:, INSTANCE=IP1, PORT=QPC1_ser, SPLY=1")
iocshLoad("$(VAC)/iocsh/QPCpump.iocsh", "PREFIX=SR:, INSTANCE=IP2, PORT=QPC1_ser, SPLY=2")
iocshLoad("$(VAC)/iocsh/QPCpump.iocsh", "PREFIX=SR:, INSTANCE=IP3, PORT=QPC1_ser, SPLY=3")
iocshLoad("$(VAC)/iocsh/QPCpump.iocsh", "PREFIX=SR:, INSTANCE=IP4, PORT=QPC1_ser, SPLY=4")

See the iocsh scripts page for full macro reference and additional examples.

Database Macro Reference

Macro	Description	Example
P	PV prefix	FE:28:ID:
PMP	Pump identifier	IP1
SPLY	Supply number (1–4)	1
SPT	Setpoint number (should match SPLY)	1
PROTO	Protocol file name (without .proto)	QPC-eth or QPC-serial
PORT	ASYN port name	QPC1

Protocol Files

Two protocol files are provided:

• QPC-eth.proto – For direct TCP connections (port 23). Uses the cmd XX command format without framing or checksum.
• QPC-serial.proto – For RS-232/RS-485 (including serial-over-Ethernet via Moxa). Uses the ~ AA XX data CC framed format with address and checksum bytes.

Records Created

Each QPCstreams.db instance creates the following records (PV names are prefixed with $(P)$(PMP):):

Record	Type	Description
Current	ai	Pump current (5s scan)
Pressure	ai	Pump pressure (5s scan)
Voltage	ai	Pump voltage (5s scan)
Status	stringin	Supply status string (5s scan)
isEnabled	stringin	HV enabled status (5s scan)
enable	bo	Enable HV on this supply
disable	bo	Disable HV on this supply
Model	stringin	Controller model (at init)
FirmwareVers	stringin	Firmware version (at init)
setPressUnits	mbbo	Set pressure units (Torr/mbar/Pascal)
getPressUnits	mbbi	Pressure units readback (10s scan)
PumpSize	ai	Pump size in L/s (at init)
setPumpSize	ao	Set pump size (30–1200 L/s)
Spt$(SPT)OnPress	ai	Setpoint on pressure readback (5s scan)
Spt$(SPT)OffPress	ai	Setpoint off pressure readback (5s scan)
Spt$(SPT)Status	bi	Setpoint relay status (5s scan)
setSpt$(SPT)OnPressure	ao	Set the on pressure for a setpoint
SptMessage	stringin	Setpoint error message display
setSpt$(SPT)OffPressure	calcout	Set the off pressure (with validation)
checkOffPressure	calcout	Validates off pressure (must be 20% > on pressure)
sendOffPressure	ao	Sends validated off pressure to device
OffSptMsg	scalcout	Generates off setpoint range messages
OffPressMsg	scalcout	Generates off setpoint status messages
OffSptMessage	stringin	Off setpoint user message display
Pump$(SPLY)Name	stringin	Pump name (15 chars max, 5s scan)

Setpoint Notes

• Setting the on pressure to a value greater than the off pressure causes the QPC firmware to automatically adjust the off pressure to be 20% greater than the on pressure.
• Setting the off pressure must be at least 20% greater than the on pressure, or the controller returns an error. The database includes validation logic to check this before sending the command.
• Valid setpoint pressure range: 1.0E-11 to 1.0E-4.

Manual st.cmd: TCP Configuration

# Configure ASYN IP port to QPC Ethernet port (TCP port 23)
drvAsynIPPortConfigure("QPC1", "192.168.1.100:23", 0, 0, 0)

# Load one instance per pump
dbLoadRecords("db/QPCstreams.db", "P=SR:,PMP=IP1,SPLY=1,SPT=1,PROTO=QPC-eth,PORT=QPC1")
dbLoadRecords("db/QPCstreams.db", "P=SR:,PMP=IP2,SPLY=2,SPT=2,PROTO=QPC-eth,PORT=QPC1")
dbLoadRecords("db/QPCstreams.db", "P=SR:,PMP=IP3,SPLY=3,SPT=3,PROTO=QPC-eth,PORT=QPC1")
dbLoadRecords("db/QPCstreams.db", "P=SR:,PMP=IP4,SPLY=4,SPT=4,PROTO=QPC-eth,PORT=QPC1")

Manual st.cmd: Serial Configuration (via Moxa Terminal Server)

# Configure ASYN IP port to Moxa serial port
drvAsynIPPortConfigure("QPC1_serial", "10.6.33.133:4002", 0, 0, 0)

# Load one instance per pump
dbLoadRecords("db/QPCstreams.db", "P=SR:,PMP=IP1,SPLY=1,SPT=1,PROTO=QPC-serial,PORT=QPC1_serial")
dbLoadRecords("db/QPCstreams.db", "P=SR:,PMP=IP2,SPLY=2,SPT=2,PROTO=QPC-serial,PORT=QPC1_serial")
dbLoadRecords("db/QPCstreams.db", "P=SR:,PMP=IP3,SPLY=3,SPT=3,PROTO=QPC-serial,PORT=QPC1_serial")
dbLoadRecords("db/QPCstreams.db", "P=SR:,PMP=IP4,SPLY=4,SPT=4,PROTO=QPC-serial,PORT=QPC1_serial")

Modbus Support

The QPCmodbus.db database uses the EPICS Modbus module to communicate with the QPC over Modbus TCP (port 502). This database currently supports a single pump and requires multiple ASYN port configurations for the different Modbus function codes.

This database is a work in progress. Status readback is not currently functional, and only a single pump is supported per database instance.

A QPC Modbus register map spreadsheet (QPC_ModbusRegisterMap_v1_3-1.xlsx) is included in the docs/ directory.

Macro Reference

Macro	Description
P	PV prefix
PMP	Pump identifier
SPLY	Supply number
SPT	Setpoint number
PORT	ASYN port for Modbus function 4 reads (voltage, current, pressure, model, firmware, MAC)
PORT1	ASYN port for Modbus function 3 reads (pump size, pump name)
PORT2	ASYN port for Modbus function 3 reads (setpoint on/off pressures, pressure units)
PORT3	ASYN port for Modbus function 6 writes (pressure units)
PORT4	ASYN port for Modbus function 5 writes (HV enable/disable)
PORT5	ASYN port for Modbus function 2 reads (setpoint status)

Example: Modbus Configuration

# Configure Modbus TCP connection
drvAsynIPPortConfigure("QPC_ETH", "192.168.1.100:502", 0, 0, 0)

# Configure Modbus ports for different function codes and register ranges
# Function 4 (Read Input Registers) - voltage, current, pressure, model, firmware, MAC
drvModbusAsynConfigure("QPC_FC4", "QPC_ETH", 0, 4, 0, 64, 0, 100, "Gamma")

# Function 3 (Read Holding Registers) - pump size, pump name
drvModbusAsynConfigure("QPC_FC3a", "QPC_ETH", 0, 3, 0, 48, 0, 100, "Gamma")

# Function 3 (Read Holding Registers) - setpoints, pressure units
drvModbusAsynConfigure("QPC_FC3b", "QPC_ETH", 0, 3, 100, 82, 0, 100, "Gamma")

# Function 6 (Write Single Register) - pressure units
drvModbusAsynConfigure("QPC_FC6", "QPC_ETH", 0, 6, 100, 1, 0, 100, "Gamma")

# Function 5 (Write Single Coil) - HV enable/disable
drvModbusAsynConfigure("QPC_FC5", "QPC_ETH", 0, 5, 0, 1, 0, 100, "Gamma")

# Function 2 (Read Discrete Inputs) - setpoint status
drvModbusAsynConfigure("QPC_FC2", "QPC_ETH", 0, 2, 0, 1, 0, 100, "Gamma")

# Load database
dbLoadRecords("db/QPCmodbus.db", "P=SR:,PMP=IP1,SPLY=1,SPT=1,PORT=QPC_FC4,PORT1=QPC_FC3a,PORT2=QPC_FC3b,PORT3=QPC_FC6,PORT4=QPC_FC5,PORT5=QPC_FC2")

GUI Displays

QPCsingle_pump_streams.adl

Display for a single QPC pump using the streamDevice database. Also available in .ui, .opi, .edl, and .bob formats.

QPCpumps_streams.adl

Display showing all four QPC pumps using the streamDevice database.

For QPC displays using the digitel record, see the ion pump controller displays.

Comparing the digitel Record and streamDevice Implementations

The QPC can be controlled through either the custom digitel record or the streamDevice databases described above. Both talk to the same hardware using the same underlying serial/TCP protocol, but they differ in several ways.

Protocol Differences

Aspect	digitel record	streamDevice
Device address	Configurable (0–255, from ASYN link)	Hardcoded to 05 in the proto file
Checksum	Computed per message (sum of bytes after ~, masked to 0xFF)	Hardcoded 00 (QPC firmware accepts this)
Setpoint read command	3C (legacy)	3B (newer, replaces 3C)
Setpoint write command	3D (legacy)	3B (newer, replaces 3D)
Voltage parsing	Integer (%d)	Float (%f)
I/O timeout	1.0 second	2.0 seconds

Setpoint Commands

The two implementations use different setpoint commands:

• The digitel record uses the legacy 3C (read) and 3D (write) commands. These are deprecated but still supported by the QPC firmware for backward compatibility.
• The streamDevice database uses the newer 3B command for both reads and writes. This is the replacement command introduced in newer firmware revisions.

The 3B command has a known issue as of firmware 1.35: readback works correctly, but setting setpoints does not work properly. The digitel record avoids this by using the older 3C/3D commands. The streamDevice database includes a @mismatch error handler that captures the error message from the controller when a write fails.

Additionally, the digitel record only reads one setpoint per pump for the QPC (the setpoint whose number matches the pump number). The streamDevice approach reads each setpoint independently through separate records.

Feature Comparison

Feature	digitel record	streamDevice
Pressure readback	Yes	Yes
Current readback	Yes	Yes
Voltage readback	Yes	Yes
Supply status	Yes	Yes
HV enable/disable	Yes	Yes
Model number	Yes	Yes
Firmware version	Yes	Yes
Pump size readback	Yes	Yes
Setpoint read/write	Yes (1 per pump)	Yes (per setpoint)
Set pressure units	–	Yes (0x0E)
Set pump size	–	Yes (0x12)
Pump name readback	–	Yes (0xED)
HV enabled query	–	Yes (0x61)
Setpoint write error feedback	–	Yes (via @mismatch)
Pump-off pressure sentinel	Yes (sets 9.9e9 when V<1000 and I<1e-6)	–
Derived pressure from I and pump size	Yes	–
Consecutive error tracking with alarm escalation	Yes	–

Architecture

The digitel record packs all functionality into a single custom record type. One record instance handles all reads (11 commands sent sequentially in a single scan cycle) and all writes for one pump. All values are stored as fields within the record.

The streamDevice database uses 27 standard EPICS records per pump (ai, ao, bi, bo, stringin, mbbi, mbbo, calcout, scalcout). Each record independently sends its own command when scanned. This is more modular but creates more PVs per pump.

When to Use Which

• Use the digitel record when you need tight integration with the existing ion pump GUI displays (Pump.adl, QPCsingle_pump.adl), alarm handling through the record’s built-in alarm fields, or compatibility with systems already using the digitel record for MPC or Digitel 500/1500 controllers.

• Use the streamDevice database when you need features like pump name readback, pressure unit control, or pump size configuration; when you prefer standard EPICS record types over a custom record; or when you want independent scan rates for different parameters.