Direct Current Current Transformer

This panel contains information concerning the keithley 2002 Multimeter (DVM). This device is used to read the Direct Current Current Transformer input value, referred to as the DCCT.

Reset DVM

This button initializes the DVM, sending a series of gpib commands. Once initialized the DVM continuously reads the DCCT hardware and stores the data into an internal memory buffer. This buffered data is then extracted by the EPICS gpib software at a preset scan period of once per second.

If the DCCT raw voltage input is not updating one solution is to reset the DVM. At times this button may need to be pressed more than once before the DVM to responds. It should be noted that resetting the DVM will set the number of power line cycles (NPLC) to a default value.

If the RESET DVM button does not fix the problem follow steps below.

Solution I:

mcc> rlogin bic06pep00
bic06pep00-> gpibsetup(0,2)
bic06pep00-> gpibcmd("DCL")

Solution II:
Reboot the ioc.

Solution III:

Drive down to IR6.

Power off the Keithley Multimeter 2000

Wait 30 seconds

Power on the Keithley Multimeter 2000

Select the RESET DVM button from the DCCT panel

Please contact Kristi Luchini or Alan Fisher if measures other then using the DVM Reset button were necessary.

Special Notes: There are two running models for the DCCT. One model uses a single DVM with a scanner card. A scanner card allows multiple channels to be read and their data to be stored in an internal memory buffer. PEP-II has two DCCT readings, one for HER and a second for LER. With a single scanner the gpib software initialize the DVM to switch between two channels, one for each DCCT value, storing the data, time and channel number. This is a working model, however, the multiplexer that allows switching between channels is slow, and so the NPLC setting is limited.

The second model uses two DVM's, one for HER and the other for LER. Since multiplexing between channels in not necessary in this case, the NPLC setting can be set at a higher rate, which in turn can supply a DCCT value which has better resolution.

Proceedure for Switching from 1 to 2 DVM's:
HW: Change hardware in IR6 (see: Alan Fisher or Kristi Luchini)
SW: log onto the gateway cddev account

opi00gtw00:cddev% bicDcctLinks 1
opi00gtw00:cddev% caput PB60:REBOOT.PROC 1
opi00gtw00:cddev% caput LB60:DCCT:RESET.PROC 1 (may need to do more than once)
opi00gtw00:cddev% caput HB60:DCCT:RESET.PROC 1 (may need to do more than once)
If the reset doesn't work then log onto the ioc and perform the steps for Solution I above, and then force processing of HB60:DCCT:RESET and LB60:DCCT:RESETagain.

Proceedure for switching from 2 to 1 DVM:
HW: Change hardware in IR6 (see: Alan Fisher or Kristi Luchini)
SW: log onto the gateway cddev account

opi00gtw00:cddev% bicDcctLinks 2
opi00gtw00:cddev% caput PB60:REBOOT.PROC 1
opi00gtw00:cddev% caput PB60:DCCT:RESET.PROC 1 (may need to do more than once)
If the reset doesn't work then log onto the ioc and perform the steps for Solution I above, and then force processing of PB60:DCCT:RESET again.

Pedestal

The pedestals should be set when PEP-II is idle. It is used as an offset for the DCCT, which is subtracted from the DCCT which is read. So if the DCCT value looks very odd, check that the pedestal value currently set.

Num Power Line Cycles

The NPLC button allows the user to enter the desired number of power line cycles per integration. The integration period (measurement speed) can also be set for the Model 2002 by setting the aperature. The aperature specifies time (in sec) per integration, while NLPC expresses the integration period by passing it on the power line frequency. If the NPLC is set too high then the user may see the Time Difference between readings to be greater than the DCCT record scan period which is currently set to 1 second.

Set DVM Date

To reset the date on the DVM, select the button labled RESET DVM DATE. This button sets the date on the Keithley 2002 Multimeter to the current Unix date from on the gateway (ie: opi00gtw00).

To set the DVM date to somthing other than the current Unix time the user should use channel access to change the value of the channel(s) listed below using the following format

Format:
        "<yr>,<mo>,<day>"
         where:
              <yr> = 19893 to 209 2       Specify year
             <mo> = 1        to 12             Specify month
             <day> = 1        to 31             Specify day

PV Channel Names:
if using one DVM
PB60:DCCT:DATE:SET

if using two DVM's
LB60:DCCT:DATE:SET
HB60:DCCT:DATE:SET

Example:
This example sets the DVM date to July 28, 2001

caput PB60:DCCT:DATESET 2001,7,28

To set the time manually from the ioc, perform the following steps.

Log onto the ioc bic06pep00

bic06pep00-> gpibsetup(0,2)
bic06pep00-> gpibsend(":syst:date <yr>,<mo>,<day>")
bic06pep00-> gpibsend(":syst:date?")

The arguments for the gpibsetup(arg1,arg2) are

agr1 = link #
arg2 = gpib device address # (ie 1-31)

If using one DVM with a scanner card installed the gpib device address
is 2. This DVM is setup to switch between both HER and LER channels
and store the data in the multimeter internal memory.

However, if using two DVM's , one for HER and one for LER
the following gpib device address apply:

LER gpib device address = 2
HER gpib device address = 3

For two DVM's follow the proceedure will setup LER, to setup HER repeat the same steps using the following arguments for gpibsetup(0,3).

Set DVM Time

To reset the time on the DVM, select the button labled RESET DVM TIME. This button sets the time on the Keithley 2002 Multimeter to the current Unix time on the the gateway (ie: opi00gtw00).

To set the DVM time to something other than the current Unix time the user should use channel access to change the value of the channel(s) listed below using the following format.

Format:
        "<hr>,<min>,<sec>"
         where:
              <hr>    = 0      to 23             Specify hour (24-hr format)
             <min> = 0      to 60              Specify minutes
             <sec> = 0.00 to 59.99         Specify seconds

PV Channel Names:
if using one DVM
PB60:DCCT:TIME:SET

if using two DVM's
LB60:DCCT:TIME:SET
HB60:DCCT:TIME:SET

Example:
This example sets the DVM time to 1:00 pm

caput PB60:DCCT:TIME:SET 13,0,0.0