Rohde & Schwarz CMU200 - IEC-Bus Interface; Interface; Interface Test; Ref in

Manual Test Procedure CMU
1100.4903.82 1.8 E–4
Interface Test
IEC-bus Interface
Preparation:
½ Connect the IEC-bus interfaces of the CMU and the controller via IEC-bus
cables.
Test: ½ Send the string ‘*IDN?<CR><NL>’ from the controller to the CMU and read the
reply STRING of the CMU.
The reply STRING must contain the following message:
‘ROHDE & SCHWARZ,CMU<Var>,<Ser_Nr>,<Firmware_Vers._Nr>’
RS–232 Interface
Preparation:
½ Connect the RS–232 interfaces of the CMU and the controller via null-modem
cables (cf. page 5.1.1, "Measuring Instruments and Auxiliary Equipment").
Set the RS–232 interface of the controller to 8 data bits, 1 start bit, 1 stop bit, no
parity bit, XON/XOFF handshake and 19200 baud.
Test: ½ Send the string ‘*IDN?<CR><NL>’ from the controller to the CMU and read the
reply string of the CMU.
The reply string must contain the following message:
‘ROHDE & SCHWARZ,CMU<Var>,<Ser_Nr>,<Firmware_Vers._No>’
Reference Frequencies
For different range of adjustment of the internal reference oscillator, the synchronization with an external
reference frequency is checked.
Note: The resolution of the frequency counter/analyzer should be max. 1/10 of the maximum
permissible deviation.
REF IN
The frequency and level ranges and the pull-in range are checked. The signal generator and the
frequency counter must be synchronized (test setup REF1).
Preparation:
½ Feed in at REF IN: 52 MHz sinewave, 0.5 V(rms)
½ Connect frequency counter to RF3 OUT.
Control: Set CMU to external reference 52 MHz, RF 1 GHz (menu RF ANALYZER/
GENERATOR.)
Test: Use frequency counter to measure frequency deviation from 1 GHz.