The SCM9B-H1750/H1770 digital I/O interface is designed to expand the remote I/O capability of the SCM9B-1700 series of modules. Commands are communicated over RS-232 or RS-485 links from any standard serial I/O port of computers or modems. The command set for the H1700 series boards is identical to the 1700 series modules.
The H1750 is designed to interface directly to either a 16- or 24-channel industry-standard solid-state relay rack (Dataforth part numbers SCMD-PB16 or SCMD-PB24). The H1770 will connect to a maximum of four 16-channel racks (SCMD-PB16). As with the SCM9B modules, up to 124 boards can be multidropped using RS-485 communications and SCM9B-A1000 repeaters.
The I/O channels may be configured to be inputs or outputs in any combination designated by the user. The input/output configuration may be changed at any time through the communications port. The I/O assignments are saved in nonvolatile memory and are automatically loaded when the unit is powered up. All boards are supplied with screw terminal plugs or ribbon connectors and captive mounting hardware.