This accessory card mounts outside the host computer and contains eight Form C electromechanical relays. (Note: Dual Form C relays are available as an extra-cost option, specify model number ROB-8A-S02.) This card is provided with stand-offs and can be mounted on your panel or you can use ACCES’ optional T-Box. ROB-8A receives outputs from Port A of any 24-bit group of any ACCES digital I/O card and Readback is provided at Port B pins. Interconnection is provided by CAB50F-xx ribbon cable.
For Remote (RS-485) control of relays, you can also connect the ROB-8A to our RDG-24.
A “Polarity Select” switch on the card provides means to select relay actuation from either high or low logic levels. An LED associated with each relay illuminates when the adjacent relay is energized. Also, Port C (high nibble) bits are coupled to screw terminals on the ROB-8A card for general digital I/O use. The lower nibble Port C bit PC2 is used for read/write select. Lower nibble Port C bits PC1 and PC0 are used for address decoding if more than one ROB-8A card is used on the same I/O port. As many as four ROB-8A’s can be connected to one 24-bit I/O port. If only one relay card is used, +5 VDC from the I/O card can power the card. If more than one ROB-8A is to be used, then there is a jumper that should be removed and external +5 VDC can be applied at screw terminals on the card(s).
If your application requires that the relays be in a known state at power-up, you may optionally specify additional 2.2 kilohm pull-up or pull-down resistors on the card. If, for example, you wish all relays to be de-activated at power-up and you will have the polarity switch set for actuation on logic HIGH inputs, then you will want pull-down resistors installed. You may specify this with model number ROB-8A-S04. Conversely, if you intend to set the switch for actuation on logic LOW inputs, then you will want pull-up resistors installed and you may specify this with model number ROB-8A-S03.
Relay outputs are brought out to eight sets of labeled screw terminals. The relays used are UL-recognized, non-latching, polarized units designed to FCC Part 68 isolation requirements. These relays can switch up to two amperes DC current with a resistive load or 1.25 amperes AC. Relays in sockets for easy replacement are available as an extra-cost option, specify model number ROB-8A-S01.