Sorry if you already know this, but on the Innform XL hit the Management access key, put in last 4 digits of prop's tel number (that's the default from tel)and hit enter .printer should print management access. Hit mode set button press 8, then hit enter. System is now in pass through mode. Anything hitting the Tel should print out. If you are not getting anything watch the led to the right of the LCD display window - that should flicker anytime SMDR hits the TEL. If still nothing plug the SMDR directly into the printer and try (if this is an InnForm XL it will have a serial printer which is already set to the same baud rate as the SMDR. If nothing there then carry the printer back to the phone room and plug directly into printer port on the PBX.

My guess is that if you are getting nothing at the CAS location it is probably a cable problem. You can always. through a mini line tester on the SMDR cable and that will tell you very quickly.