HONEYWELL 05704-A-0121 ISS.03 QUAD RELAY INTERFACE CARD - 5704 Instructions

HONEYWELL 05704-A-0121 ISS.03 QUAD RELAY INTERFACE CARD - 5704 Instructions

The 5701 and 5704 control systems provide a complete solution for the operational and engineering requirements of a multi-channel fire and gas detection system. Each control card within the rack system provides sensor drive, signal acquisition, gas concentration display and comprehensive alarm facilities for one or more fire or gas sensors. The MODBUS Interface facility extends the capability of the control system by providing an external computer system with monitoring and control functions for every gas sensor or fire detector connected to the rack. The operation and alarm integrity of the System 57 is not affected by the MODBUS Interface. The digital data link uses a bi-directional 8-bit asynchronous serial connection that is configurable for baud rate, parity and stop bits. Two different modules are available, one supports both RS485 and RS422 electrical interface standards and the other supports the RS232 electrical interface standard. Depending upon the module type, system configuration and the capability of the host computer, various communication options are available as follows: Interface Transmission Dual Highway Multi-drop Mode Option Option RS485 Half Duplex Yes Yes (31 Nodes) RS422 Half Duplex No Yes (10 Nodes) RS232 Half Duplex No No The dual highway option provides a secondary or backup data link for increased communication integrity. Multi-drop configurations allow a single communication line to be shared by a number of devices reducing the number of communication ports required at the host computer. RS232 provides the lowest cost solution for connecting a single System 57 rack to a host computer. RS485 provides the best solution for multi-drop connection of more than one System 57 rack to a host computer and also gives the option of a secondary highway. RS422 is useful to provide multi-drop connection where the host computer software does not have the facility for transceiver direction control (transmit/receive/high impedance) that is required with RS485 connections.

In all cases the System 57 operates as a MODBUS Remote Terminal Unit (RTU), acting as a slave device node and transmitting data onto the communication line only in response to a request from a master device. The host computer system, typically a PLC, DCS or SCADA graphics package, acts as the master device controlling the communication system operation. The subset of MODBUS functions supported by the System 57 RTU are 02, 03, 04, 06 and 16. The MODBUS broadcast commands are not supported and will be ignored, however, global commands are available to reset all cards in the rack simultaneously. For a detailed description of the available commands and data formats refer to the System 57 MODBUS Function Reference given in Section 7. 2.2 MODBUS INTERFACE MODULE - RS485/422 2.2.1 General The RS485/422 Interface Module has two differential 5V transceivers designated channel 1 and channel 2. Each transceiver channel can be resistively terminated by setting LK1 and LK2 respectively (see Figure 1 and Section 3.4.3). The interface signals are isolated from the System 57 power supply 0V and Ground to protect the host computer against damage due to earth loops. 2.2.2 RS485 Operation An outline RS485 connection diagram is shown in Figure 4. When configured for the RS485 mode, transceiver Channel 1 is used in dual highway systems for the primary highway or the only highway in single highway systems. Transceiver Channel 2 is used only in dual highway systems where it functions as the secondary highway. Depending upon the type of installation, operation is possible over distances up to 1.2km (3900ft). In the multi-drop mode up to 32 nodes, including the host, can be connected. The terminal connections are: CH1-A, CH1-B Differential Transceiver Channel 1 (Primary). CH2-A, CH2-B Differential Transceiver Channel 2 (Secondary). DGND Isolated Data Ground. In a dual highway system the MODBUS uses, at any one time, only one of the two available highways, either the primary or the secondary. The interface automatically switches between highways when a communication failure is detected.

The highway switching process is controlled as follows:

a. The inactive highway is continuously monitored for data

communication.

b. If data communication is detected on the inactive highway, the

inactive highway is assumed to be fully serviceable.

c. If valid data communication ceases on the active highway and the

inactive highway is perceived to be serviceable, the MODBUS

interface switches between channels.

When configured for RS422 mode, transceiver Channel 1 is used for transmission from the System 57 RTU to the host computer and transceiver Channel 2 is used as a receiver for transmissions from the host computer to the System 57 RTU. Depending upon the type of installation, operation is possible over distances up to 1.2km (3900ft). Although the EIA RS422 standard specifies only point to point applications, the addressable operation of System 57 permits a modified 'broadcast' mode topology that allows multi-drop connection of up to 10 nodes. Each System 57 node is held in a high impedance state until it receives an appropriately addressed request, when it enables its transmitter for the duration of the response. The terminal connections are: TX-A, TX-B Differential Transceiver Output from RTU. RX-A', RX-B' Differential Receiver Input to RTU. DGND Isolated Data Ground

The RS232 Interface Module has transmit and receive data lines and two handshaking lines. The interface conforms to the RS232 standard giving ±12V output drive. Depending upon the type of installation, operation is possible over distances up to 15m (49ft). To protect the host computer against damage due to earth loops, the interface signals are isolated from the System 57 power supply 0V and Ground. The terminal connections are designated as follows: RXD Receive Data input to RTU. TXD Transmit Data output from RTU. DSR Data Set Ready input to RTU. DTR Data Terminal Ready output from RTU. SGND Isolated Signal Ground.

There are two versions of the Engineering Card. The MODBUS Interface Kit can only be fitted to the Mk 2 Engineering Card. With the Engineering Card removed from the rack, the type of Engineering Card can be visually identified as follows: a. Mk I hardware by the presence of only one 28 pin DIL IC socket on the card pcb. b. Mark II hardware by the presence of two 28 pin DIL IC sockets and a rectangular cutout near the centre of the card pcb. (See Figure 7). A summary of the MODBUS Interface installation procedure is shown below: a. Unpack and check the contents of the kit. b. Remove the Engineering Card from the rack. c. Install the Software Expansion EPROM Integrated Circuit. d. Install the RAM Expansion Integrated Circuit. e. Install the MODBUS Interface Module. f. Wire the DC Input Card terminal blocks to the host computer. g. Configure and Commission After installation is complete perform the commissioning procedures outlined in Section 5. The following sections provide a detailed explanation of the installation operations.

On receipt carefully unpack the equipment observing any instructions printed on or contained in the packaging. Check the contents for transit damage and ensure that the following items are present:

For the MODBUS Interface Module Kit: RS485/422: a. MODBUS Interface Module RS485/422 (05701-A-0282). b. Engineering Card Expansion Option EPROM integrated circuit (05701-A-0385). c. RAM expansion integrated circuit type HN6264ALP. d. User Manual (05701-A-5006). For the MODBUS Interface Module Kit RS232: a. MODBUS Interface Module RS232 (05701-A-0287). b. Engineering Card Expansion Option EPROM integrated circuit (05701-A-0385). c. RAM expansion integrated circuit type HN6264ALP. d. User Manual (05701-A-5006). 3.3 INSTALLING THE MODBUS INTERFACE KIT Except for Step (6) which applies to the RS485/422 Module only, the following installation procedure applies to both versions of the MODBUS Interface Kit: (1) Isolate the SYSTEM 57 Rack from all power sources. (2) Unscrew the two front panel screws that retain the Engineering Card and using the extraction tool supplied with the system pull the Engineering Card from the rack.

(3) Insert the Software Upgrade EPROM integrated circuit (05701-A0385) into the socket IC2 on the Engineering Card, ensuring that pin 1 of the IC is aligned correctly with pin 1 of the socket and that all pins are properly inserted into the socket. Note: If an IC is already fitted to socket IC2, this should be removed and discarded.

(4) Insert the RAM expansion integrated circuit (HN6264ALP) into the socket IC12 on the Engineering Card, ensuring that pin 1 of the IC is aligned correctly with pin 1 of the socket and that all pins are properly inserted into the socket. (5) Using small pliers or an electrical screwdriver gently remove the Engineering Card shorting link LK1 and replace to short pins 1 and 2. See Figure 7. (6) This step applies to the RS485/422 module only. For correct operation, especially at high baud rates, RS485 and RS422 highways should be resistively terminated. In RS422 host systems, a terminator resistance is only required at the receiver device located in the host and at the receiver device located in the System 57 node at the far end of the cable. In RS485 host systems, a terminator resistance is required at the transceiver device located in the host and at the transceiver device located in the System 57 node at the far end of the cable. For dual highway RS485 systems, both highways should be terminated as described above. By default the RS485/422 module transceivers are unterminated. If a resistive termination is required, use small pliers or an electrical screwdriver to gently remove the shorting links, LK2 (Channel 1) or LK1 (Channel 2), on the RS485/422 Module from pins 1 and 2 and replace to short pins 2 and 3. (See Figure 1 and Section 3.4.3). (7) Insert the MODBUS Interface Module into the socket headers J1 and J2 on the Engineering Card, ensuring that pin 1 of the module pin headers is correctly aligned with pin 1 of the Engineering Card socket headers. (8) Re-insert the Engineering Card into the rack, tighten the two front panel screws and go to the Section 3.4.