View source for 7501T8

Model 7501T8 is a solid-state relay (SSR) rack that accommodates up to eight G4 type SSR modules. It has a 50-pin header which is compatible with several Sensoray GPIO products, including models 826 and 2410.

==Pinout==

{| class="wikitable" style="text-align:center"
! colspan="3" | 7501T8
! colspan="3" | GPIO
|-
! rowspan="2" | SSR<br>Socket
! rowspan="2" | Header<br>Pin
! rowspan="2" | TB Pins<br>(+/-)
! colspan="2" | Model 826
! rowspan="2" | Model<br>2410
|-
! J3 !! J4
|-
| 0 || 47 || 1/2   || 0 || 24 || 17
|-
| 1 || 45 || 3/4   || 1 || 25 || 19
|-
| 2 || 43 || 5/6   || 2 || 26 || 21
|-
| 3 || 41 || 7/8   || 3 || 27 || 23
|-
| 4 || 39 || 9/10  || 4 || 28 || 9
|-
| 5 || 37 || 11/12 || 5 || 29 || 11
|-
| 6 || 35 || 13/14 || 6 || 30 || 13
|-
| 7 || 33 || 15/16 || 7 || 31 || 15
|}

==Using with Sensoray 826==

You must supply 5 VDC power to the relay rack. This can be done in either of the following ways:
* Connect an external 5 VDC power source to the relay rack's +5V and GND terminals. The 5 VDC power source must share a common ground with the computer power supply.
* On the bottom of the relay rack, attach a wire (via solder) from the +5V terminal to J1 pin 49. This will use +5 V from the 826 board to power the relay rack.

The relay rack can be connected to header J2 or J3 on the 826 board. The Pinout table (see above) shows the GPIO associated with each SSR, which depends on whether the relay rack is connected to J2 or J3. For example, if the relay rack is connected to J2 then SSR2 will be associated with GPIO26.

An output SSR is controlled by writing to the associated GPIO, whereas an input SSR is monitored by reading the GPIO. Model 826 has active-low GPIOs and the relay rack is designed for active-low signaling. Consequently, you must write '1' to turn on an output SSR and write '0' to turn it off. Similarly, when reading an input SSR, '1' indicates the relay is on and '0' indicates off.