12 34980A Service Guide
2 Specifications
Multiplexer Module Specifications and Characteristics 
[1]
 DC or AC RMS voltage, channel-to-channel or channel-to-earth 
[2]
 Peak voltage, channel-to-channel or channel-to-earth
[3]
 Into analog bus. System errors are included in the internal DMM measurement accuracy specifications.
[4]
 With in-rush resistors bypassed. Bypassing resistors reduces lifetime of relays. See the rated load relay life characteristics.
[5]
 Limited to 6 W of channel resistance power loss per module
[6]
 DC or peak AC current
[7] 
Ambient temperature < 30 °C
[8]
 Includes 0.5 °C temperature reference sensor and 0.5 °C terminal block isothermal gradient error.  Measured under worst case 
loading of the mainframe. See 34980A User's Guide for information on supported  external reference sensors. 
[9] 
With 100  input protection resistors.
34921A 34922A 34923A 34924A 34925A
Channels/configurations 40 2-wire
20 4-wire
4-current
1.5 A Fused
70 2-wire
35 4-wire
80 1-wire
40 2-wire
20 4-wire
70 2-wire
35 4-wire
80 1-wire
40 2-wire
20 4-wire
Switch type Armature 
latching
Armature 
latching
Reed Reed
Optically 
isolated FET
Input characteristics (per channel)
Max volts ± 300 V 
[1]
± 300 V 
[1]
± 150 V peak 
[2]
± 150 V peak 
[2]
± 80 V peak 
[2]
Max current (DC, AC RMS)
Switch current
Carry current
1 A
2 A
1 A
2 A
0.5 A
[4]
/0.05 A
[9]
1.5 A
[4]
/0.05 A
[9]
0.5 A
[5]
/0.05 A
[9]
1.5 A
[5]
/0.05 A
[9]
0.02 A
[6]
Power (W, VA) 
[5]
60 W 60 W 10 W 10 W 1.6 W
Volt-Hertz limit 10
8
10
8
10
8
10
8
10
7
Initial closed channel res 
[3][10]
 
< 1.5  < 1.5  < 1.5 
5
/200 
9
< 1.5 
5
/200 
9
< 700 
General specifications
Offset voltage 
[3]
< 3 V< 3 V < 50 V
< 100 
V 1-wire
< 50 V< 3 V
DC Isolation (ch-ch, ch-earth) >10 G >10 G >10 G >10 G >10 G
Leakage current 
[3]
N/A N/A N/A N/A 20 nA 
[7]
T/C cold junction accuracy 
[3, 8]
  < 1 °C N/A N/A N/A N/A