List of 34980A Measurement Capabilities
•Temperature measured with Thermocouples, RTDs and Thermistors
•DC and AC volts
•2- and 4-wire Resistance
•Frequency and Period
•DC and AC current
•4 alarms for High/Low or both limits for each channel
•Digital I/O
•Analog outputs (DAC)
The 34980A mainframe also includes four 2-wire internal analog buses. This is a differentiating 34980A feature and not included with the 3499A/B/C. The analog buses can be used to route measurements directly to the internal DMM or connect the mainframe modules to external instruments. The analog bus can be used to extend modules such as the matrix switch modules, or provide additional signal routing between modules.
Mainframes
The 34980A Multifunction Switch/Measure Unit consists of an eight-slot mainframe with an optional DMM. The DMM is mounted directly behind the front panel so it does not require any of the available eight module slots. A choice from 19 different modules can be plugged directly into the eight-slot mainframe.
In comparison, the 3499 Family has mainframes in three different sizes: A, B, and C that house five, two, and nine modules respectively. The 3499 Family offers a selection of 30 plug-in modules, 13 of which are the earlier generation HP 3488A Switch/Control Unit modules. Since some of the modules were designed for the 3488, and some modules specifically for the 3499, there is duplicate functionality between the modules.
As test systems and capability needs expand there is a call for a greater number of switch channels within one system. The 34980A switch modules are designed for high switching channel count. The 34980A eight- slot mainframe fully loaded with 2-wire multiplexer modules houses a total switch channel count of 560. The 3499C nine-slot mainframe fully loaded with 2- wire multiplexer modules houses a total of 360 switch channels. For a quick summary of the maximum switch channel count for the switch systems mainframes, see Table 1.
Mainframe | Mainframe Size | Number of Module Slots | Maximum Number |
| | | of Channels (2-wire) |
34980A | Full Rack, 3U | 8 | 560 |
3499B | Rack, 2U | 2 | 80 |
3499A | Half Rack, 2U | 5 | 200 |
3499C | Full Rack, 5U | 9 (electrical)/ | 360 |
| | 14 (physical) | |
Table 1. Max 2-wire Mux channel count per Mainframe
