Revised November 19, 1990
Revised January 17, 1992
Jim Harwood
Following is a description of the Forth commands issued from the remote PC computer to cause the TCS to perform certain functions. In all cases, the commands must be in upper case and have arguments delimited by spaces before the command (standard Forth protocol).
These commands may be typed in for testing at either the LSI-11 or at the remote computer in terminal emulation mode. The TCS response to the commands will be exactly the same, whether the commands are issued from a terminal or from a program.
The end-of-stream prompt from the LSI-11 is –OK<cr><nl>. This sequence (without the period) occurs at the end of the transmission from the LSI-11 and will always occur, whether or not other data is transmitted. If an LSI-11 transmission consists of multiple lines, the lines are ended with <cr><nl>.
In this document, ASCII strings returned to the remote
computer from the LSI-11 are printed in typewriter style. Actual text is
in upper case; lower case italics indicates a general format of the returned
data, such as hh:mm:ss.
ASCII strings sent to the LSI-11 are printed here in BOLDFACE.
(a) LSI-11 Response Formats:
You may need to know the exact format of the responses returned by the TCS LSI-11. In the examples in this document, the fields of the LSI-11 response are separated by more than one space for clarity. They actually are always separated by only one space. The fields are fixed format with respect to the number of characters in each field and the number of decimal places. For further information, see the author.
IMPORTANT NOTE: Some of these commands have a "wait for motion complete" option. The LSI-11 computer will hold off returning to the remote computer until completion of the instructions to move the telescope. However, the telescope may still be physically moving, since there is an inertial lag in the telescope response. The TCS does not check for this inertial lag. If this is important, you are advised to hold off the next operation for a second or two after the reply comes back from the LSI-11.
Also, use of the "wait for motion complete" may cause the communications link between the remote computer and the TCS to time out, creating a "comproc" error. The communications link at the remote computer expects the TCS to respond within a second or two to the transmitted command. Use the "wait for motion complete" option with care.
1. Telescope position, epoch commands
1.1 n TPD
Argument:
n = 0 for requesting immediate reply.
n = 1 for requesting wait for any offset-type motion to complete.
Request current telescope position data. The data returned for RA, dec, HA, airmass, and epoch are from the same variables that are read out on the monitor display.
Returns:
Current telescope coordinates as follows‑
|
|
RA |
DEC |
HA |
AIRMASS |
EPOCH |
|
|
|
hh:mm:ss:ss |
dd:mm:ss:s |
hh:mm:ss:ss |
a.aaa |
yyyy.y |
-OK |
Returns from the TCS, after any offsetting has finished,
|
|
14:26:11.84 |
32:56:38.6 |
-01:44:29.21 |
1.187 |
1950 |
-OK |
1.2 n LSP
Argument:
n = 0 for requesting immediate reply.
n = 1 for requesting wait for current slew to complete.
Request last-entered slew position and epoch. In case the last-entered slew was aborted, the data returned are 0 0 0.
Returns:
Last entered slew coordinates and epoch as follows‑
|
|
RA |
DEC |
EPOCH |
|
|
|
hh:mm:ss:ss |
dd:mm:ss:s |
yyyy.y |
-OK |
Returns from the TCS, after the current slew is finished, its coordinates and epoch as-
|
|
9:23:41.84 |
41:19:55.6 |
1950.0 |
-OK |
1.3 yyyy.y
C.EPOCH
Argument:
Year in tenths. (0.0 for APPARENT.)
Requests a change of epoch, or if the argument is 0.0, a change from MEAN to APPARENT. If the original state was APPARENT, and a non-zero epoch is requested, the state will change to MEAN.
The TCS sends back as confirmation the new epoch preceded by the telescope coordinates corresponding to the shift in epoch.
Returns:
Telescope coordinates corresponding to the new epoch‑
|
|
RA |
DEC |
HA |
AIRMASS |
EPOCH |
|
|
|
hh:mm:ss:ss |
dd:mm:ss:s |
hh:mm:ss:ss |
a.aaa |
yyyy.y |
-OK |
Returns from the TCS‑
|
|
14:26:11.84 |
32:56:38.6 |
-01:44:29.21 |
1.187 |
1950.0 |
-OK |
2. Beamswitch commands
2.1 ABEAM
BBEAM
Calls for positioning the telescope to the A-beam or B-beam logical position. (See >BEAM< for altering the logical to physical beam relationship.)
No data are returned from the TCS, except the usual –OK.
2.2 ?BEAM
Returns the current beam state.
Returns from the TCS‑
ABEAM
–OK or BBEAM -OK
2.3 >BEAM<
Toggles the current beam designation without moving the telescope, and reports back the logical beam state. Thus, the first time >BEAM< is used, logical beam A becomes physical beam B and vice versa. The second time >BEAM< is used, the logical and physical beams are the same.
The logical beam is the designation within the program, and the physical beam is the actual telescope's beam position.
Sends back from the TCS, if the current beam is B, without moving the telescope‑
ABEAM –OK
2.4 ?BS
Returns the current beamswitch position as a displacement from the beamswitch base position. The units are tenths arcseconds, positive for North and East. The RA coordinate difference has been multiplied by cos(dec) to produce the returned on-sky RA beamswitch displacement.
Current telescope beamswitch displacement (after any pending beamswitch motion) as follows‑
|
|
RA |
DEC |
|
|
|
sss.s |
sss.s |
-OK |
Returns from the TCS ‑
-10.5 –OK
The return says that the telescope is currently zero arcseconds RA and 10.5 arcseconds south of the beamswitch base position.
2.5 ra.s
dec.s TW.BS
Arguments:
ra.s is desired right ascension displacement in arcseconds.
dec.s is desired declination displacement in arcseconds.
Sets entered displacements in beamswitch thumbwheel locations as if the displacement were in the console thumbwheels. The displacements are positive for East and North. Subsequent beamswitch commands will cause the displacements to occur, such as pressing the beamswitch pushbutton or calling ABEAM or BBEAM. The right ascension displacement given is assumed to be an on-sky displacement, not coordinate difference. The value is divided by cosine(dec) prior to being applied to the telescope HA axis.
Displacements of 10.0 arcseconds east and 20.0 arcseconds south will occur when ABEAM is called. The telescope will return to the beamswitch base position when BBEAM is called.
2.6 ?TW.BS
Returns the beamswitch displacements last entered in the thumbwheels. Assumes the associated pushbuttons were pressed so that the beamswitch thumbwheel data would be entered into the computer.
The units are tenths arcseconds, positive for North and East. The RA coordinate difference as applied to the telescope is derived by dividing the RA beamswitch thumbwheel data by cos(dec). Thus the RA thumbwheel data represent the on-sky RA beamswitch displacement.
Current thumbwheel beamswitch data as follows‑
|
|
RA |
DEC |
|
|
|
sss.s |
sss.s |
-OK |
Returns from the TCS ‑
1.1 –OK
The return says that the data in the beamswitch thumbwheels is 5.0 arcseconds west and 20.0 arcseconds north relative to the beamswitch base position.
3. Offset commands
3.1 n DO.OFFST
Argument:
n = 0 for requesting immediate reply.
n = 1 for requesting wait for current offset to complete.
Causes the telescope to offset the amount entered in the offset thumbwheels relative to the base offset position. (If the telescope is already at that position, nothing happens.)
Nothing is returned from the TCS, except the usual –OK.
3.2 n -DO.OFFST
Argument:
n = 0 for requesting immediate reply.
n = 1 for requesting wait for current offset to complete.
Places the telescope back to the offset base position. If it is already there, nothing happens.
Only the –OK is returned from the TCS.
3.3 ?OFFST
Returns the current offset position as a displacement from the offset base position. The units are tenths arcseconds, positive for North and East. The RA offset coordinate difference has been multiplied by cos(dec) to produce the returned on-sky RA beamswitch displacement.
Current telescope offset displacement (after any pending offset motion) as follows‑
|
|
RA |
DEC |
|
|
|
sss.s |
sss.s |
-OK |
Returns from the TCS ‑
-44.6 -211.5 –OK
The return says that the telescope is currently 44.6 arcseconds west and 211.5 arcseconds south of the offset base position.
3.4 ra.s
dec.s TW.OFFST
Arguments:
ra.s is desired right ascension displacement in arcseconds.
dec.s is desired declination displacement in arcseconds.
Sets entered displacements in offset thumbwheel locations as if the displacements were in the console thumbwheels. The displacements are positive for East and North. Subsequent offset commands will cause the displacements to occur, such as pressing the offset pushbutton (PB4) or calling DO.OFFST or –DO.OFFST. The right ascension displacement given is assumed to be an on-sky displacement, not coordinate difference. The value is divided by cosine(dec) prior to being applied to the telescope HA axis.
Displacements of 23.6 arcseconds east and 41.8 arcseconds south will occur when Pushbutton 4 is pressed the first time, or n DO.OFFST is called. The telescope will return to the offset base position when Pushbutton 4 is pressed again or n -DO.OFFST is called.
3.5 ?TW.OFFST
Returns the offset thumbwheel settings as entered at the console or by calling TW.OFFST. The units are tenths arcseconds, positive for North and East. Note that the mechanical thumbwheels are not read; what is read are the memory locations that receive the thumbwheel data when the associated pushbutton is pressed.
Console offset thumbwheel data, or equivalent entered with command TW.OFFST, as follows‑
|
|
RA |
DEC |
|
|
|
sss.s |
sss.s |
-OK |
Returns from the TCS ‑
-44.6 -211.5 –OK
The return says that the previously entered offset displacement data is 44.6 arcseconds west and 211.5 arcseconds south. The telescope would displace this far from the offset base position if Pushbutton 4 were pressed or command DO.OFFST given.
3.6 ra.s
dec.s OFFSET
OFFSET takes ra and dec displacement parameters (10ths arcsecs) and causes the offset to occur. Do not use this command if any scanning is used, since OFFSET uses scanning software facilities and therefore would conflict with a scan in progress. In that case, use the command TW.OFFST instead to set the displacement and DO.OFFST or –DO.OFFST to execute it.
4. Scan commands
4.1 r sss.s
sss.s c C.SCN
Argument:
r is a reply code:
r = 0 for immediate reply.
r = 1 to wait for this scan motion to complete before replying.
sss.s: RA arcseconds displacement, then dec arcseconds.
c is a command code:
c = 0 for relative displacement.
c = 1 for absolute displacement.
c = -1 to initialize the current scan position without moving telescope (defines this as scan base position).
Displacements are positive for East and North. The displacement given for RA should be the on-sky displacement. This value will be divided by cos(dec) to produce a coordinate difference for output to the telescope.
Scanning patterns in the sky are done with this command. The scan motions are independent of offsetting or beamswitching. The displacements sss.s arcseconds are with respect to the scan base position when using 1 for argument c, and are with respect to the previous scan position when using 0 for this argument.
To specify the current telescope position as the scan base reference, -1 is used for argument c. In this case, the values of sss.s for RA and dec are "don't care".
To cause the telescope to return to the scan base position, the arguments should be r 0.0 0.0 1, where r is either 0 or 1.
Returns the –OK from the TCS after the scan motion is complete. The telescope is moved 21.3 arcseconds east and 100.0 arcseconds south of its previous scan position.
4.2 ?SCAN
Returns the current scan position as a displacement from the telescope's scan base position. The units are tenths arcseconds, positive for North and East. The RA coordinate difference has been multiplied by cos(dec) to produce the returned on-sky RA scan displacement.
Current telescope scan displacement (after any pending scan motion) as follows‑
|
|
RA |
DEC |
|
|
|
sss.s |
sss.s |
-OK |
Returns from the TCS ‑
-216.8 49.3 –OK
The return says that the telescope is currently 216.8 arcseconds west and 49.3 arcseconds north of the scan base position.
5. Peak commands
5.1 r sss.s
sss.s c C.PEAK
Argument:
r is a reply code:
r = 0 for immediate reply.
r = 1 to wait for this peak motion to complete before replying.
sss.s: RA arcseconds displacement, then dec arcseconds.
c is a command code:
c = 0 for relative displacement.
c = 1 for absolute displacement.
c = -1 to initialize the current peak position without moving telescope (defines this as peak base position).
Displacements are positive for East and North. The displacement given for RA should be the on-sky displacement. This value will be divided by cos(dec) to produce a coordinate difference for output to the telescope.
Peak patterns in the sky are done with this command. The peak motions are independent of offsetting, beamswitching, or scanning. The displacements sss.s arcseconds are with respect to the peak base position when using 1 for argument c, and are with respect to the previous peak position when using 0 for this argument.
To specify the current telescope position as the peak base reference, -1 is used for argument c. In this case, the values of sss.s for RA and dec are "don't care".
To cause the telescope to return to the peak base position, the arguments should be r 0.0 0.0 1, where r is either 0 or 1.
Returns the –OK from the TCS after the peak motion is complete. The telescope is moved 4.5 arcseconds east and 10.0 arcseconds south of its previous peak position.
5.2 ?PEAK
Returns the current peak position as a displacement from the telescope's peak base position. The units are tenths arcseconds, positive for North and East. The RA coordinate difference has been multiplied by cos(dec) to produce the returned on-sky RA peak displacement.
Current telescope peak displacement (after any pending peak motion) as follows‑
|
|
RA |
DEC |
|
|
|
sss.s |
sss.s |
-OK |
Returns from the TCS ‑
-86.3 29.7 –OK
The return says that the telescope is currently 86.3 arcseconds west and 29.7 arcseconds north of the peak base position.
6. Autoguider commands
6.1 r sss.s
sss.s c C.AUTOG
Argument:
r is a reply code:
r = 0 for immediate reply.
r = 1 to wait for this autoguider motion to complete before replying.
sss.s: RA arcseconds displacement, then dec arcseconds.
c is a command code:
c = 0 for relative displacement.
c = 1 for absolute displacement.
c = -1 to initialize the current autoguider position without moving telescope (defines this as autoguider base position).
Displacements are positive for East and North. The displacement given for RA should be the on-sky displacement. This value will be divided by cos(dec) to produce a coordinate difference for output to the telescope.
Autoguider motions in the sky are done with this command. The autoguider motions are independent of offsetting, beamswitching, or scanning. The displacements sss.s arcseconds are with respect to the autoguider base position when using 1 for argument c, and are with respect to the previous autoguider position when using 0 for this argument.
To specify the current telescope position as the autoguider base reference, -1 is used for argument c. In this case, the values of sss.s for RA and dec are "don't care".
To cause the telescope to return to the autoguider base position, the arguments should be r 0.0 0.0 1, where r is either 0 or 1.
Returns the –OK from the TCS after the autoguider motion is complete. The telescope is moved 4.6 arcseconds east and 1.4 arcseconds south of its previous autoguider position.
6.2 ?AUTOG
Returns the current autoguider position as a displacement from the telescope's autoguider base position. The units are tenths arcseconds, positive for North and East. The RA coordinate difference has been multiplied by cos(dec) to produce the returned on-sky RA autoguider displacement.
Current telescope autoguider displacement (after any pending autoguider motion) as follows‑
|
|
RA |
DEC |
|
|
|
sss.s |
sss.s |
-OK |
Returns from the TCS‑
-16.1 23.8 –OK
The return says that the telescope is currently 16.1 arcseconds west and 23.8 arcseconds north of the autoguider base position.
6.3 !V.AUTOG
Stores the given autoguider velocity in arcseconds/sec. This velocity will be resolved along the two axes when an autoguider displacement is executed. The RA component will be divided by cos(dec) so that the on-sky velocity is uniform anywhere in the sky. The entered velocity should be unsigned.
6.4 ?V.AUTOG
Returns the current autoguider velocity in arcseconds/sec. Zero means maximum possible velocity.
Current telescope autoguider velocity as follows: v.s -OK
Returns from the TCS: 20.0 –OK
7. Other commands
7.1 rpm.ttt
dpm sss hh:mm:ss.s dd:mm:ss.s
yyyy.y C.SLEW
Argument:
RA thousandths seconds time and declination hundredths arcseconds proper motion, right ascension and declination coordinates, epoch
Provides the TCS with the coordinates and epoch for a desired object. The TCS applies the proper motion to the apparent coordinates and reduces the mean coordinates to apparent. If the year is 0., the TCS assume4s the provided coordinates are apparent.
Return is immediate, without waiting for the TCS to slew to the object. Only the –OK is returned.
7.2 C.HST
Returns civil HST in 50ths seconds in the format ttttttt. The count goes up to 24 hours.
7.3 C.STIME
Returns sidereal time in the format hh:mm:ss.ss.
Returns from the TCS the sidereal time as follows:
8:41:19.8 –OK
7.4 ?DISP
Returns the current total displacement from the telescope base position, including beamswitch, offset, scan, and guiding. Waits for any currently active displacing to finish. The units are tenths arcseconds, positive for North and East. The RA coordinate difference has been multiplied by cos(dec) to produce the returned on-sky displacement.
Current telescope displacement (after any pending displacement motion) as follows‑
|
|
RA |
DEC |
|
|
|
sss.s |
sss.s |
-OK |
Returns from the TCS:
-44.6 -211.5 –OK
The return says that the telescope is currently 44.6 arcseconds west and 211.5 arcseconds south of the base position.
7.5 PB8
Resets the current total position as the base position for all offset-from-base functions except SCAN. You need to explicitly call C.SCN with the appropriate parameters to define the scan base position.
7.6 TCSINFO
Returns telescope status information. Exactly equivalent to doing 0 TPD C.STIME C.HST.
8. Pointing commands
These commands are special purpose commands to be used in the utility that performs a skymap for determining the pointing error coefficients.
8.1 n SKYMAP
Argument:
n = 0 if skymap not finished.
n = 1 if this is the last star in the skymap.
The SKYMAP command waits for the reply from the TCS. The reply is received after the console button is pressed indicating that the current skymap star is on the crosshairs. Returned data consists of the star coordinates and setting errors.
NOTE: This command has not been completely implemented, in that the LSI-11 needs to be programmed to send the data over the RS-232 link rather than the DR11 link.
Returns:
Telescope apparent refracted position at the time Pushbutton 6 was pressed, and the net guiding displacement representing the ideal-actual position, as follows:
|
|
HA |
del(HA)secs T |
DEC |
del(DEC)arcs |
|
|
|
hh:mm:ss:ss |
t.tt |
dd:mm:ss.s |
ss.s |
-OK |
where the deltas have positive signs for North and West.
8.2 +PTNG
-PTNG
These commands tell the TCS that console Pushbutton 6 is to be used for a pointing skymap (+PTNG) or that it is to revert to its usual function (-PTNG).