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DC Relay Wildcard Users Guide

Easily control DC devices from your embedded microcontroller based instrument

This users manual shows you how to use the DC Solid State Relay WildCard™. It provides an overview of the hardware and software for the Wildcard as well as a schematic.

The DC Solid State Relay Wildcard allows you to control up to three, 3 amp DC loads. You can stack up to eight DC Relay Wildcards on to your Mosaic controller or a Wildcard Carrier Board or you can mix and match any of the other WildCards. The following sections guide you through the DC Relay Wildcard’s hardware and software.



DC Relay Wildcard Specifications
Channels: Three independent, optically isolated DC solid state relays
Voltage: Controls 3 - 60 VDC
Current: Switches up to 3 A continuously, 12 A surge for 10 msec.
Isolation: Optically isolated to 2500 V rms
Maximum ON Voltage Drop: 0.4 VDC
Maximum OFF Leakage Current: 100 μA
Turn On/Off Times: Max turn on/off times of 50/300 μsec
Operating Temperature: -30 to +80 °C
Connections: Easy-to-connect-to screw terminals
SSR Used: Crydom DMO-063 DC solid state relay
Current: FIXME mA from 5V
Weight: 34 gram
Size : 2" x 2.5" x 0.575"1) (50.8mm x 63.5mm x 14.6mm)



The DC Relay Wildcard was designed to allow easy control of DC loads. Each DC Relay provides:

  • Control of 3 to 60 VDC loads up to 3 amps.
  • Max surge current of 12 amps for 10 ms.
  • Optically isolated control to 2500 Vrms.
  • Max turn on time of 50 μsec.
  • Max turn off time of 300 μsec.
  • integrated flyback and surge protection for inductive loads.

For more technical information, please consult the data sheet for the Crydom DMO063. The next section shows you how to connect the DC Relay Wildcard to a Mosaic controller or a Wildcard Carrier Board and how to configure the Wildcard for proper operation.


Connecting the Wildcard to a Mosaic controller

To connect the DC Relay Wildcard to the Wildcard Bus of a Mosaic controller, follow these simple steps:

While the power is OFF, connect the DC Relay Wildcard's bus connector to your controller's Wildcard Port 0 or Wildcard Port 1 header (These may also be called Module Port 0 or 1). If you are using a Wildcard Carrier Board, connect the DC Relay Wildcard to the QED Board (as shown in the Wildcard Carrier Board Users Guide). The corner mounting holes on the Wildcard should line up with the standoffs on your controller.

The Wildcard Bus on the DC Relay Wildcard is located opposite from its screw terminal connector.

Caution -- connectors are not keyed!
The DC Relay Wildcard Bus does not have keyed connectors. Be sure to insert the DC Relay Wildcard so that all pins are connected. The Mosaic controllers and the DC Relay Wildcard can be permanently damaged if the connection is done incorrectly.

Selecting the Wildcard Address

Once you've connected the DC Relay Wildcard to the Mosaic controller or the Wildcard Carrier Board, you must set the address of the Wildcard using jumper shunts across J1 and J2.

The Wildcard Select Jumpers, labeled J1 and J2, select a 2-bit code that sets a unique address on the wildcard port of the Mosaic Controller. Each wildcard port on the Mosaic controller accommodates up to 4 wildcards. Wildcard Port 0 on the Mosaic controller provides access to wildcards 0-3 while Wildcard Port 1 provides access to wildcards 4-7. Two wildcards on the same port cannot have the same address (jumper settings). Here are the possible jumper settings and the corresponding addresses:

Address Jumper Settings
Wildcard Port Wildcard Address Installed Jumper Shunts
0 0 None
0 1 J1
0 2 J2
0 3 J1 and J2
1 4 None
1 5 J1
1 6 J2
1 7 J1 and J2
Note:<block indent>Address 0 is not available on the QScreen or Handheld. Use addresses 1 through 7 instead.</block>

Once you have connected and configured all of the hardware properly, you can use the software drivers for instrumentation, or to control DC loads.



This section describes the software that enables you to control the DC Relay Wildcard. We first start with a description of how wildcards are addressed, then move on to how the relays are controlled, and finally present you with example software that initializes and controls the relays.


Initializing the Wildcard

The functions IOStoreChar, IOFetchChar, IOSetBits, and IOClearBits are used to communicate with the DC Relay Wildcard. These functions take an offset address and Wildcard address. These functions are provided in QED_QCard_IO.4th for V4.xx kernels, but are native to the V6.xx kernel. This file can be found in:

Mosaic\Wildcard Drivers\Libraries\include\

The DC Relays on the DC Relay Wildcard are controlled by a Xilinx CPLD (Complex Programmable Logic Device). The DC Relay control lines on the CPLD must be configured as outputs for proper operation (on power up, the control lines are initialized as inputs). To initialize the module, execute the Init_DC_Relay function as shown in the demonstration programs.

Once you have initialized the module, use Control_DC_Relay to turn on or off the relays and Read_DC_Relay_Status to read the status of all the relays. Note that the control lines are active low, which means that to turn a relay on, you have to write a 0 to the relay.


C demo program for the DC Relay Wildcard

The c demo is located in your installation directory. You can also view it online here.


Forth demonstration program

The forth demo is located in your installation directory. It is also provided here for reference.
After sending the demo to your board type:


to run the demo with the DC wildcard installed on port 0.



Now you are ready to start controlling instruments with your DC Relay Module. All of the software routines listed in this document are also included with the development environment provided with your Mosaic controller starter kit.


DC Relay Wildcard schematic

Relay Datasheet

Height is from the bottom of the PCB to the top of the tallest component on the top side of the PCB.
This page is about: 3 Amp Optically Isolated DC SSR (Solid State Relay) for OEM Instruments, Uses Crydom DC Relay Modules, Users Manual – Users manual for controlling DC loads with large surge tolerance using Crydom DC optically isolated solid state relays. DC Relay, Solid State, Opto isolated, hardware, screw terminals, 12 amp max surge current, control lines