Features and Functions 4
Keysight 34970A/34972A User’s Guide 177
Relay cycle count
The instrument has a Relay Maintenance System to help you predict relay
end-of-life. The instrument counts the cycles on each relay in the instrument and
stores the total count in non-volatile memory on each switch module. You can use
this feature on any of the relay modules and the internal DMM.
– In addition to the channel relays, you can also query the count on backplane
relays and bank relays. Note that you cannot control the state of these relays
from the front panel but you can query the count. For more information on
channel numbering and layout, refer to “Module Overview” starting on page
209.
– You can also query the state of the three relays on the internal DMM. These
relays are numbered “1”, “2”, and “3” (which correspond to relays K102, K103,
and K104 respectively). These relays open or close when a function or range is
changed on a module.
– The 34908A multiplexer contains 40 channels which are switched (HI only)
using only 20 relays. Each relay is used to switch HI on two different channels
(and only one channel can be closed at a time). The channels are arranged
such that channels 01 and 21 use different contacts on the same relay. The
remaining channels are also paired in the same manner (channels 02 and 22,
channels 03 and 23, etc.). Therefore, when you query the relay count on a
channel, the number reflects the number of times that the relay was closed.
For example, the relay count will always be the same on channels 01 and 21.
– You can reset the count (allowed only from remote) but the instrument must be
unsecured (see “Calibration Overview” on page 198 to unsecure the
instrument).
– For more information on relay life and load considerations, refer to “Relay Life
and Preventive Maintenance” starting on page 337.
– Front-Panel Operation: To read the count on the active channel, choose the
following item and then turn the knob. To read the count on the internal DMM
relays, turn the knob counterclockwise beyond the lowest numbered channel
in the instrument. To read the “hidden” backplane and bank relays, turn the
knob clockwise beyond the highest numbered channel in the current slot.
RELAY CYCLES
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