Issue
What needs to be done when using 2 readers in parallel and 1 D9210B or D9210C, but the readers are not working?
Solution
The D9210B/C module can support two readers in parallel, both readers will show access granted but it is not possible to tell the direction of travel. Two D9210B/C modules would be better because you can see a direction of travel. If using two K3003 or D8303 readers connected in parallel on a D9210B/C that are not working, there is a work around for this issue. (Same goes for any of the 3000 series KEY PAC Readers. ) Diodes can be used, 4 required, one diode for each Data 0 and Data 1 wire. Place the diode with the negative band towards the reader, use either a Standard Purpose Diode # 1N4003 (standard recovery rate), or a Glass Switching Diode # 1N914A (Fast Recovery Rate) for this application
