STATION AND PERIPHERAL ADDRESSING

SPERRY UTS 30 SINGLE STATION

System Reference UP-9799 Rev. 1

In this example, the poll solicits traffic from the UTS 30. The UTS 30 responds with a message conveying data, status, or a combination thereof. The host signifies proper receipt of the message from the station by including an acknowledgment in the next poll to that station. The station responds with a no-traffic message, indicating that it received the acknowledgment and has nothing further to send at this time.

3.1.2. Host Processor Text Message to UTS 30 - Message Sequence

After sending a text message to a UTS 30 single station, the host processor must always send a poll to verify that the station received the text message correctly. If the station response to the poll contains an acknowledgment, then the text message was received correctly by the station. If the station response to the poll does not contain an acknowledgment, then the station did not receive the host text message correctly.

The basic message sequence required to send text from the host processor to a UTS 30 station is as follows:

Host Processor Text

Poll

Poll with acknowledgment

Direction of

Transmission UTS30

Response containing an acknowledgment*

No traffic

In the preceding message sequence, the host processor sends a text message to the UTS 30 single station and then polls to determine whether or not the text message was received correctly (that is, with good character and block parity). The station responds to the poll with an acknowledgment, indicating it received the text message correctly. The host processor then signifies proper receipt of the station acknowledgment in the next poll to that station. The station then responds with a no-traffic message, indicating that it received the acknowledgment and has nothing further to send.

3.2. STATION AND PERIPHERAL ADDRESSING

The host uses an addressing scheme to direct its messages to the proper UTS 30 or peripheral.

This routing information uses a 3-number (hexadecimal) sequence consisting of a remote identifier (RID), a station identifier (SID), and a peripheral device identifier (DID). In addition, the host may address messages to all of the stations and peripherals on its communications line by using a general identifier (GID). The allowable address ranges are listed in 3.2.1.

Each communication line has a specific RID. Each display screen on each UTS 30 single station on a communicatio~s line has its own SID. Therefore, the address of a station is symbolized by a unique RID SID. (Note, however, that stations on different communications lines may have duplicate SIDs. It is the RID SID combination that must be unique.) Each peripheral assigned to a station has its own DID. Specific DIDs for peripheral selection are discussed in 3.8.

UP-9799 Rev. 1

SPERRY UTS 30 SINGLE STATION

System Reference 3-3

All messages (except no-traffic) contain the 3-hexadecimal number address, symbolized in the messages as RID SID DID, immediately following the start-of-header (SOH) character. (See 3.4 for communications control message formats.)

3.2.1. Operator Selection of Addresses

RID, SID, and DID addresses are selected by the operator through the control page or the configurator utility. See Appendix J and the operator's reference for the UTS 30, UP-9798 (current version). The address ranges are:

• RID - hexadecimal 21 through 7F

• SID - hexadecimal 21 through 7E

• DID - hexadecimal 20 through 7E NOTES:

1. Three numbers are reserved by the host for sending general messages. The G/Ds are: SP (hexadecimal 20) is the general RID, P (hexadecimal 50) is the general SID, and p (hexadecimal 70) is the general DID.

2. The host may restrict the RID to 21 through 4F and the SID to 51 through 6F.

3. D/Ds 70, 71, 72, and 7F should be avoided, as they have special host functions.

4. The number of DID selections in compatible UN/SCOPE and UTS 400 display terminals is limited to 12: from hexadecimal 73 through 7E. To avoid confusion, the sample message sequences in this section will be restricted to D/Ds in this range.

3.2.2. Poll Groups

A poll group is defined as all stations on the communications line that recognize the RID and SID of a poll message. Each station in such a group will recognize a general RID as its own RID address and a general SID as its own SID address.

A poll containing a general RID, general SID, and general DID is called a general poll. Another form of a general poll is one containing a specific RID, general SID, and general DID. The general polls used in the examples in this section all contain a specific RID, general SID, and general DID. A poll containing a specific RID, specific SID, and general DID is called a specific poll.

Figure 3-1 illustrates two examples of poll groups that would respond to a general poll (specific RID, general SID, general DID) from the host. The terminal multiplexer group consisting of three UTS 30 stations defines a poll group with a common RID of "1." Note that the second screen associated with the UTS 30 has a SID designation of its own. A UTS 30 second screen with no other stations on the drop represents a poll group with a RID of "2." Each of these poll groups illustrated is connected on a multidrop line with each poll group representing a drop on the multidrop line.

All the stations in a poll group addressed by a general poll are candidates to furnish the response. A UTS 30 with a second screen behaves similarly to a terminal multiplexer (described in 3.6) in terms of determining priority of response between the station and the second screen memory.

3-4

HOST PROCESSOR

MODEM

P= PERIPHERAL

SPERRY UTS 30 SINGLE STATION System Reference

MODEM

TERMINAL MULTIPLEXER

UTS 30

RID= 1

SID= e NOTE:

UTS 30

RID= 2 SID= a

DID= s

UTS 30

DID= s

UTS 30 RID= 1 SID= a

RID= 1 SID= c

DID= t

EACH UTS 30 IS ASSIGNED TWO CONTIGUOUS SIDS:

UP-9799 Rev. 1

ALTERNATE SCREEN

RID= 2 SID= b

ALTERNATE SCREEN

RID= 1 SID= d

TERMINAL SCREEN= ASSIGNED SID DID =w

ALTERNATE SCREEN= SID+ 1 (AUTOMATICALLY ASSIGNED)

UP-9799 Rev. 1

SPERRY UTS 30 SINGLE STATION

System Reference 3-5

No two drops on a multidrop line can be members of the same poll group. Both drops would try to respond at once because there is no means to resolve the contention for the line. Note, however, that more than one poll group may be associated with a terminal multiplexer (if multiple RIDs are assigned), providing multiple poll groups at a physical drop.