A 9-pin SUB-D female connector AUX on the rear panel provides a +5.2 V supply. The pin assignment is as follows:
AUX connector
| Pin | Signal | Input (I) / Output (O) / Bidirectional (B) |
Description |
| 1 | GND | B | GND |
| 2 | +5VKEYB | O | Power supply +5.2 V, max. 100 mA |
| 3 | GND | B | GND |
| 4 | I2CSDA | B | For future extensions |
| 5 | I2CSCL | O | For future extensions |
| 6 | GND | B | GND |
| 7 | RESERVE4 | B | |
| 8 | RESERVE5 | B | |
| 9 | RESERVE6 | B |
The 15-pin SUB-D female connector AUX 3 on the front panel is used as an input or output for status, control, and trigger signals. These signals are applied to particular (in some function groups: selectable) pins of the AUX 3 connector (refer to the corresponding menu).
The pin assignment of the AUX 3 connector is as follows:
AUX3 connector
| Pin | Signal | Input (I) / Output (A) / Bidirectional (B) |
Description |
| 1 | GND | B | |
| 2 | TBUS1 | O | Timing output A Test signal CH1 GSMxxx-MS Signalling: Frame trigger Bluetooth Signalling: Signalling trigger |
| 3 | TBUS2 | O | Timing output B |
| 4 | TBUS3 | O | Timing output C |
| 5 | TBUS4 | O | Timing output D |
| 6 | TBUS5 | I | External trigger input
CMU300: |
| 7 | TBUS6 | I | External trigger B |
| 8 | TBUS7 | I | External trigger A External trigger signal CH1 input for Spectrum and Power measurements |
| 9 | GND | B | GND |
| 10 | GND | B | GND |
| 11 | GND | B | GND |
| 12 | GND | B | GND |
| 13 | GND | B | GND |
| 14 | GND | B | GND |
| 15 | GND | B | GND |
The 15-pin SUB-D female connector AUX 4 on the rear panel is used as an input or output for status, control, and trigger signals. These signals are applied to definite pins of the AUX 4 connector (refer to the corresponding menu).
The pin assignment of the AUX 4 connector is as follows:
AUX4 connector
| Pin | Signal | Input (I) / Output / Bidirectional (B) |
Description |
| 1 | GND | B | GND |
| 2 | GND | B | GND |
| 3 | GND | B | GND |
| 4 | GND | B | GND |
| 5 | GND | B | GND |
| 6 | GND | B | GND |
| 7 | GND | B | GND |
| 8 | GND | B | GND |
| 9 | TBUS8 | B | Status/control/trigger signal |
| 10 | TBUS9 | B | Status/control/trigger signal |
| 11 | TBUS10 | B | Status/control/trigger signal |
| 12 | TBUS11 | B | Status/control/trigger signal |
| 13 | TBUS12 | B | Status/control/trigger signal |
| 14 | TBUS13 | B | Status/control/trigger signal |
| 15 | TBUS14 | B | Status/control/trigger signal |