I cannot find the external control (DIGITAL I/O) connector for PCR-WE/WEA series. Where is it stored?

The DIGITAL I/O connector for each model is stored as follows:
PCR-WE series:
– PCR1000WE/2000WE/3000WE2: Supplied as an accessory.
– PCR-6000WE2 and higher capacity models: Stored by default on the back of the control panel.

PCR-WEA series:
– PCR1000WEA/2000WEA/3000WEA2 (Ver. 3.xx and 4.xx models): Supplied as an accessory.
– PCR-6000WEA2 and higher capacity models of Ver.3.xx: Stored by default on the back of the control panel.
– All Ver.4.xx models: Supplied as an accessory.