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HYDRA
Service Manual
4-20
To provide accuracy at full range, calibration is not recommended below one-third of
full range (10000 counts).
Table 4-8. Calibration Mode Computer Interface Commands
Command Description
Cal x Start calibration of a new function.
x Function to calibrate
1VDC
2 VAC
3 ohms
4 Frequency
CAL_CLR Reset all calibration constants to nominal values, clearing present calibration.
CAL_CONST? xx Return the value of the calibration constant indicated by xx.
CAL_REF? Return the present calibration reference.
CAL_REF < value> Calibrate to <value>, rather than the default calibration reference value.
CAL_STEP? Calibrate and return the calibrated value of the input.
EEREG? xx Return the contents of the specified EEPROM register (xx).
The following additional computer interface commands can be used in calibration mode. Use of any other
command results in an execution error. Refer to Section 4 of the Hydra Users Manual for complete
information about these computer interface commands.
*CLS *ESE *ESE?*ESR?*IDN?*OPC *OPC?*RST *SRE *SRE?*STB?*TRG *WAI IEE IEE?IER?LOCS
LWLS REMS RWLS
4-21. Using Hydra Starter Calibration Software
This procedure uses the Hydra Starter Package (with Calibration Software) for closed-
case calibration. This software runs on an IBM PC or equivalent using the RS-232
interface. It consists of the following three files:
• An executable file (CAL.EXE)
• A help text file (CAL.HLP)
• A configuration initialization file (CAL.INI)
4-22. Setup Procedure Using Starter
Use the following procedure to set up Hydra and the PC prior to using the calibration
feature of the Hydra Starter Package:
1. Connect a pair of test leads to the channel 1 H (high) and L (low) terminals on the
Input Module. Connect a second pair of test leads to channel 11. (This second pair is
used only for 4-wire resistance calibration.) Install the Input Module into Hydra.
2. Using the RS40 Terminal Interface Cable, connect the PC COM port to the Hydra
RS-232 port. Use an RS40 and an RS41 cable in series to connect to the COM port
on an IBM PC/AT.