DESCRIPTION

The Ortec MCS-pci Multichannel Scaler has count rates up to 150 MHz and up to 65,536 channels. Dwell times are selectable from 100 nanoseconds to 1300 seconds per channel. spec can control up to four MCS-pci modules.

FUNCTIONS

See the mca help file for a description of the mca_get(), mca_put() and other standard MCA-type functions available in spec.

mca_par("clear")

Clears the data memory of the MCS.

mca_par("run")

Programs the MCS device with the appropriate parameters and starts acquisition. If "auto_clear" mode is set, clears the current data, otherwise, continues acquisition. The pass count is zeroed in both cases.

mca_par("auto_clear" [, value])

With no arguments, returns nonzero or zero to indicate whether auto-clear mode is set. Otherwise sets the mode to value. When auto-clear mode is set, the MCS data is cleared before data acquisition is started.

mca_par("halt")

Halts the current pass if acquisition is active. If entered a second time before the pass completes, the acquisition is terminated without completing the current pass.

mca_par("dwell" [, value])

With no arguments, returns the current dwell value. Otherwise, sets the dwell to value. A negative argument selects external dwell. Valid values are from 100e-9 to 1300 seconds.

mca_par("npts" [, value])

With no arguments, returns the current number of points or pass length. Otherwise, sets the pass length to value. Allowed values are from 4 to 65,536.

mca_par("passes" [, value])

With no arguments, returns the current preset passes value. Otherwise, sets the passes preset to value. A value of zero indicates no preset.

mca_par("preset" [, value])

The "preset" argument has the same function as "passes".

mca_par("elapsed_passes")

Returns the number of elapsed passes since acquisition started.

mca_par("current_bin")

Returns the current channel number of the current pass. The first channel is numbered zero.

mca_par("input" [, which])

Returns the string "sca" or "disc" to indicate which input is used as the signal source. String arguments of of "sca" or "disc" for which select the setting.

mca_par("impedance" [, value])

Returns 50 or 1000 to indicate whether the discriminator input impedance is set to 50 ohms or 1 kohm. An argument of 50 or 1000 for value sets the input impedance. The default value is 1 kohm.

mca_par("disc_level" [, value])

With no arguments, returns the current discriminator threshold level. Otherwise sets the threshold to value. Valid values are from -1.6 to +3.0V with steps of 0.0015256V.

mca_par("disc_edge" [, which])

Returns the string "rising" or "falling" to indicate whether the discriminator is rising-edge or falling-edge sensitive. String arguments of of "rising" or "falling" for which select the setting.

mca_par("sca_low" [, value])

With no arguments, returns the current lower-level threshold value of the SCA input. Otherwise sets the threshold to value. Valid values are from 0 and +10V with steps of 0.002442V.

mca_par("sca_high" [, value])

With no arguments, returns the current upper-level threshold value of the SCA input. Otherwise sets the threshold to value. Valid values are from 0 and +10V with steps of 0.002442V.

mca_par("trigger" [, which])

Returns the string "internal" or "external" to indicate whether new passes are started automatically or require an external trigger. The optional argument which can be either of the strings "internal" or "external" to select the trigger source.

mca_par("trig_level" [, value])

With no arguments, returns the current external channel-advance threshold level. Otherwise sets the threshold to value. Valid values are from -1.6 to +3.0V with steps of 0.0015256V.

mca_par("reset")

Stops acquisition, clears data memory and restores all MCS parameters to default values, as follows:

mca_par("dwell", 1e-7)
mca_par("npts", 1000)
mca_par("passes", 0)
mca_par("input", "disc")
mca_par("impedance", 1000)
mca_par("disc_level", 1.4)
mca_par("disc_edge", "rising")
mca_par("sca_high", 6.5)
mca_par("sca_low", 1.2)
mca_par("trigger", "internal")
mca_par("trig_level", 1.4)

mca_par("dump")

Displays current MCS parameters.

mca_par("chan#")

Returns the contents of channel number #.

mca_par("chan#", value)

Set the contents of channel number # to value.