"""B&K Precision 8500B-series E-Load driver. Covers 8500B/8502B/8510B/8514B/8542B (shared SCPI surface).
Hardware-validated against the 8514B; other family members are expected to work but have not been bench-tested.
"""
from instro.eload import ELoadDriverBase
from instro.eload.types import LoadMode, SlewRateDirection
from instro.lib.transports.visa import VisaConfig, VisaDriver
def loadmode_to_unit(mode: LoadMode) -> str:
return {
LoadMode.CC: "CURR",
LoadMode.CV: "VOLT",
LoadMode.CP: "POW",
LoadMode.CR: "RES",
}[mode]
[docs]
class BK85XXB(ELoadDriverBase):
"""B&K Precision 8500B-series E-Load (8500B/8502B/8510B/8514B/8542B).
Hardware-validated against the 8514B; others share the SCPI surface but have not been bench-tested.
"""
def __init__(self, visa_resource: str | VisaConfig) -> None:
self._visa = VisaDriver(visa_resource)
[docs]
def open(self) -> None:
self._visa.open()
self._write_checked("SYST:REM")
[docs]
def close(self) -> None:
self._visa.close()
[docs]
def short_output(self, enable: bool, channel: int) -> None:
with self._visa.lock():
self._visa.write(f"INPut:SHORt {int(enable)}")
self._visa.write(f"INPut {int(enable)}")
self._check_errors()
[docs]
def set_mode(self, mode: LoadMode, channel: int) -> None:
self._write_checked(f"FUNCtion {loadmode_to_unit(mode)}")
[docs]
def set_level(self, mode: LoadMode, value: float, channel: int, curr_limit: float | None) -> None:
if mode is LoadMode.CV:
pass # TODO add CV→CC protection based off curr_limit
self._write_checked(f"{loadmode_to_unit(mode)} {value}")
[docs]
def set_range(self, mode: LoadMode, value: float, channel: int) -> None:
if mode not in (LoadMode.CC, LoadMode.CV):
raise NotImplementedError(
f"BK85XXB only exposes :RANGe for CC and CV; {mode.value} is auto-ranged from the level value"
)
self._write_checked(f"{loadmode_to_unit(mode)}:RANGe {value}")
[docs]
def set_slewrate(self, direction: SlewRateDirection, rate: float, channel: int) -> None:
self._write_checked(f"CURRent:SLEW:{direction.value} {rate}")
[docs]
def output_enable(self, enable: bool, channel: int) -> None:
self._write_checked(f"INPut {int(enable)}")
[docs]
def get_current(self, channel: int) -> float:
return self._query_checked_float("MEASure:CURRent?")
[docs]
def get_voltage(self, channel: int) -> float:
return self._query_checked_float("MEASure:VOLTage?")
def _write_checked(self, command: str) -> None:
with self._visa.lock():
self._visa.write(command)
self._check_errors()
def _query_checked_float(self, command: str) -> float:
with self._visa.lock():
value = self._visa.query(command)
self._check_errors()
return float(value)
def _check_errors(self) -> None:
err = self._visa.query("SYST:ERR?")
if not err.startswith("0"):
raise RuntimeError(f"BK85XXB reported error: {err}")
instro