10. Relay Cards

Chapter 10 describes the features of the relay card, one of the I/O cards designed for the Smart Star embedded control system.

The Smart Star is a modular and expandable embedded control system whose configuration of I/O, A/D converter, D/A converter, and relay cards can be tailored to a large variety of demanding real-time control and data acquisition applications.

The typical Smart Star system consists of a rugged backplane with a power supply, a CPU card, and one or more I/O cards. The CPU card plugs into a designated slot on the backplane chassis, which has seven additional slots available for I/O cards to be used in any combination. A high-performance Rabbit 2000 microprocessor on the CPU card operates at 25.8 MHz to provide fast data processing.

10.1 Relay Card Features

Two models of relay cards are available, as shown in Table 18.

Table 18. Smart Star Relay Cards

I/O Card	Model	Features
Relay	SR9500	5 SPST relays and 1 SPDT relay, each protected with onboard snubbers
	SR9510	8 SPDT relays (no snubbers)

The SR9500 relay cards are suitable for switching all kinds of loads up to 30 V DC at 1 A or 48 V AC at 0.5 A. The SR9510 handles similar loads, but is restricted to noninductive loads unless you add snubbers to the system that is interfacing with the Smart Star.

10.2 User Interface

Depending on the model of relay card (see Table 18), the relays on the relay card will be configured as SPDT or SPST with or without snubbers. Figure 45 shows these relay configurations.

Figure 45. Relay Configurations

The diode protects the coil power supply (and the Smart Star backplane) from inductive spikes caused by energizing/de-energizing the coil, and the resistor-capacitor snubbers protect the relay contacts against voltage spikes induced by inductive loads.

Figure 46 shows the complete pinout for the user interface on header J1. Note that pin 1 is indicated by a small arrow on the ribbon cable connector.

Figure 46. Relay Card User Interface Pinout

10.3 User FWT Connections

Connections to the relay cards are made via a ribbon cable connector or optional field wiring terminals that are either pluggable or have screw terminals. Table 19 lists the Z-World part numbers for the FWTs.

Table 19. Guide to FWT Selection

FWT Description	I/O Cards	Z-World Part Number
		Pluggable Terminals	Screw Terminals
FWT18R	Relay (SR9500)	101-0422	101-0426
FWT27	Relay (SR9510)	101-0420	101-0424

10.3.1 Pinouts

Figure 47 shows the pinout for the FWTs used on the relay cards.

Figure 47. FWT Pinouts for Relay Cards

10.4 Power Distribution

Figure 48 shows the power distribution on the relay card.

Figure 48. Relay Card Power Distribution

The relay coil actuation voltage is 12 V, and so +V_USER should be 12 V to 30 V DC. The +V_USER supply passes through a linear regulator and comparator, which are in parallel. The comparator is set for approximately +13.9 V, and as long as +V_USER is more than +13.9 V, the +12 V from the linear regulator will provide the coil actuation voltage. Should +V_USER be less than +13.9 V, the comparator will supply +V_USER directly to provide the coil actuation voltage.

10.5 Relay Cards Software

Dynamic C Premier is an integrated development system for writing embedded software. It runs on an IBM-compatible PC and is designed for use with Z-World controllers and other controllers based on the Rabbit microprocessor.

10.5.1 Dynamic C Libraries

With Dynamic C running, click File > Open, and select Lib. The following list of Dynamic C libraries and library directories will be displayed.

One library directory is specific to the Smart Star.

• SMRTSTAR--libraries associated with features specific to the Smart Star control system.

10.5.2 Library Directories

The SMRTSTAR directory contains libraries required to operate the Smart Star control system.

• SMRTSTAR.LIB--This library supports all the functions needed by the Smart Star systems including digital I/O cards, relay cards, D/A converter and A/D converter cards, and serial communication.

10.5.3 Smart Star Relay Card Function APIs

void relayOut(int relay, int value);

Sets the state of a relay.

Parameter

relay is the relay to set. relay should be passed as

relay = (slotnumber * 128) + (relaynumber)

or

relay = ChanAddr(slotnumber, relaynumber)

where slotnumber is 0-6, and relaynumber is 0-5 (SR9500) or 0-7 (SR9510), depending on the model of relay card.

value is the value to set the relay to, 0 or 1 (off or on).

10.5.4 Sample Programs

• SSTARRLY.C--Demonstrates turning a relay on the relay card on and off.

10.6 Using Dynamic C

To run a sample program, open it with the File menu (if it is not still open), compile it using the Compile menu, and then run it by selecting Run in the Run menu. The CPU card must be in Program Mode (see Section 4.1, "Programming Cable") and must be connected to a PC using the programming cable as described in Section 2.3, "Programming Cable Connections."

More complete information on Dynamic C is provided in the Dynamic C Premier User's Manual.

10.7 Electrical and Mechanical Specifications

Figure 49 shows the mechanical dimensions for the relay card.

Figure 49. Relay Card Dimensions

NOTE	All diagram and graphic measurements are in inches followed by millimeters enclosed in parentheses.

Table 20 lists the electrical, mechanical, and environmental specifications for the relay card.

Table 20. Relay Card Specifications 

Parameter	Specification
Board Size	2.73" × 3.00" × 0.44" (70 mm × 76 mm × 11 mm)
Connectors	one 2 × 17 latch/eject ribbon connector, 0.1 inch pitch
Operating Temperature	-40°C to +70°C
Humidity	5% to 95%, noncondensing
Power Requirements	5 V DC at 10 mA from backplane (+5 V supply) 12 V to 30 V DC, 10 mA at 24 V DC, +RAW/+V_USER from backplane
Relay Switching Contacts	30 V DC at 1 A or 48 V AC at 0.5 A
Relays	SR9500: 1 SPDT, 5 SPST (N.O., COM) with snubbers SR9510: 8 SPDT (N.O., N.C., COM), no snubbers

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