This is a current production model however the only reference to it is a 6/10/2003 announcement on the "What's New" page. Call Ten-Tec for info.
The Model 311 converts the open collector outputs of the Orion to the active high inputs required by the Model 253 and Model 420. The output voltage per line is approx. 13.5VDC and each line is capable of driving loads requiring 40mA (each line is current limited to 40mA). Each output uses an MMBT3906 transistor with a breakdown voltage of 40VDC. So it is important that no more than 40VDC is ever applied to any of these lines. Most applications would never require that DC be applied to any of the pins anyway.