Omega A2400 - Manual

Functional Description 2-2 EEPROM MICRO-PRCESSOR +5 5.6K DO0/RTS RX TX CTS RTS +5V UART RX TX DEFAULT Figure 2.1 A2400 Block Diagram.

Functional Description 2-4 bus. This bus connects to multidrop RS-485 devices such as D seriesmodules. 8) (G)DATA- This is the negative polarity of the differential RS-485 bus. 9) (R)V+ A2400 power connection. The A2400 operates on 10 to 30 volts dc. 10) (B)GND This is the ground connection common t...

Functional Description 2-5 reaching the RS-485 bus. The first operation performed on the modem data is to check for noise andframing errors. If either condition exists, the bad character is re-formatted asa null character (ASCII $00). Since the null is not a legal character for useas an address in t...

Functional Description 2-6 addressed command and it responds back with information on the bus. TheA2400 receives this information and places it in a buffer that can hold up to96 characters. The parity of received characters is ignored. As soon as acharacter is received, the A2400 starts a timing seq...

Functional Description 2-7 T1As soon as the A2400 detects a character in the RS-485 receive buffer, timedelay T1 is activated. This is a dead time to allow the host to prepare for thereceipt of a message. This is particularly important when a simplex connec-tion is used, where the send and receive d...

Communication 3-2 improper command prompt or address is transmitted. The table below liststhe timeout specification for each command assuming that delay times T1,T2, T3 = 0: Table 3.1 Response Timeout Specifications.Mnemonic Timeout DO, OC, CC, RD, REA, RID, RLP, RS, RSP, RSU, ≤ 10 ms RT1, RT2, RT3,...

Chapter 4 A2400 Command Set The A2400 operates with a simple command/response protocol to controlall module functions. A command must be transmitted to the A2400 by thehost computer or terminal before the A2400 will respond with useful data. Amodule can never initiate a communications sequence. A li...

Command Set 4-7 Command DescriptionsAll the commands may be used with normal addressing or ExtendedAddressing unless otherwise noted. Commands that are exclusive to theExtended Address mode are noted near the right hand margin. For example: Closed Channel (CC) (Extended) Closed Channel (CC) (Extende...

Command Set 4-8 To turn the output off you could use the command: Command: $1DO00 Response: * Command: #1DO00 Response: *1DO004E Digital output 0 shares the connector pin with the Alternate RTS. Bit 3 of byte4 of the SetUp command is used to configure this pin as either digital outputor RTS function...

Chapter 5 Setup Information/SetUp Command The A2400 features a wide choice of user configurable options which givesthem the flexibility to operate on virtually any radio or leased-line modem.The user options include a choice of baud rate, parity, address, and manyother parameters. The particular cho...

SetUp Command 5-2 A typical SetUp command would look like: $1SU31070102 Notice that each byte is represented by its two-character ASCII equivalent.In this example, byte 1 is described by the ASCII characters ‘31’ which is theequivalent of binary 0011 0001 (31 hex). The operand of a SU commandmust co...

Delay Time Programming 6-2 Figure 6.1 Programmable delay times. As described in figure 6.1 the communications sequence assumes a hostcomputer communicating with a module on the RS-485 bus through theA2400. In an idle condition, when no data is present on the communications lines,the A2400 turns its ...

Delay Time Programming 6-3 the data over the RS-485 bus. This data is normally command data beingsent to a module on the bus. When the RS-232 command data is complete,the A2400 immediately turns its RS-485 transceiver back to receive modeand monitors the RS-485 bus. In normal operation the A2400 loo...

Delay Time Programming 6-4 Command: $1T3+00050.00 (set T3 to 50 ms.) Response: * Time may be set to 1 ms. resolution. The T1, T2, T3 commands are write-protected and must be preceded by aWrite Enable (WE) command. The delay times are stored in nonvolatile memory. The delay times are inactive in Defa...

Chapter 7 Power Supply A2400 modules may be powered with an unregulated +10 to +30Vdc.Power-supply ripple must be limited to 5V peak-to-peak, and the instanta-neous ripple voltage must be maintained between the 10 and 30 volt limitsat all times. All power supply specifications are referred to the mo...

Chapter 8 Troubleshooting Symptom: RS-232 Module is not responding to commands 1 Using a voltmeter, measure the power supply voltage at the +Vs and GND terminals to verify the power supply voltage is between +10 and+30Vdc. 2 Verify using an ohmmeter that there are no breaks in the communica- tions d...

Chapter 9 Extended Addressing The A2400 may be configured to a special command format called ExtendedAddressing. This mode uses a different prompt, either ‘{‘ or ‘}’ to distinguishit from the regular command syntax. The major difference in syntax for theExtended Addressing mode is that it uses a two...

Extended Addressing 9-2 Figure 7.1 Typical system overview.

Extended Addressing 9-3 When the system is initially powered up, the A2400’s are set to the CloseChannel condition. This means that no data received by the radio modemswill pass to the RS-485 bus at either site. In order to communicate to themodules, one of the A2400’s must be set to the Open Channe...

Extended Addressing 9-4 Figure 7.1 shows a very simple system but the same addressingmethodmay be used to construct very large systems. Each RS-485 stringmay handle up to 122 addresses, and up to 14884 A2400’s may have uniqueaddresses. Structured AddressingEven for a relatively small system, it can ...

Extended Addressing 9-5 All commands that are available with single-byte addressing may beaccessed with Extended Addressing, and vice-versa; the only exceptionsbeing the OC and CC commands, which can be used only with ExtendedAddressing. OC and CC Command FormatsOnce an A2400 has been configured cor...

Extended Addressing 9-6 This command will close the channel at A2400 #01 and open the channelat A2400 #02. This is the quickest method of opening and closing A2400channels. It also offers the least amount of data security. A2400 #01 wasclosed solely upon detecting the ‘{‘ character. There is no conf...

Extended Addressing 9-7 To explicitly close the channel of A2400 #01: Command: {01CC Response: * The response message is a confirmation that the channel has been closed.A higher level of confirmation can be obtained with the long form: Command: }01CC Response: *01CC11 (‘11’ is the checksum) The resp...

Chapter 10 Transparent Mode The A2400 is an RS-232/RS-485 converter designed to provide interfacevirtually any product to a radio and leased telephone line modems. In normaloperation the A2400 is configured to work on the D series protocol, but it maybe configured to a special communications mode ca...

Transparent Mode 10-3 Example 2. A2400 networking several RS-232 devices to a host com-puter. Figure 10.2 A2400 networking several RS-232 devices to a host computer.

Transparent Mode 10-5 Example 4. A2400 interfacing several instruments with a string ofmodules.

Transparent Mode 10-6 Figure 10.5 Adding secondary control using A2400 modules.

Transparent Mode 10-7 Figure 10.5 shows an application where the user was able to add a back-upor secondary control supervision using the A2400 modules. The originalinstallation of the flow computers and PLC’s were controlled by the controlstation using Modbus protocol with RS-485. The user was able...

WARRANTY/ DISCLAIMER O M E G A E N G I N E E R I N G , I N C . w a r r a n t s t h i s u n i t t o b e f r e e o f d e f e c t s i n m a t e r i a l s a n dworkmanship for a period of 13 months from date of purchase. OMEGA’s WARRANTY adds an additional one (1) month grace period to the normal one (1...

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